//must be compiled with c++20 
/*
#pragma GCC target ("avx2")
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")
*/
#include <algorithm>
#include <bits/stdc++.h>
#include <cerrno>
#include <ext/pb_ds/assoc_container.hpp>
#include <type_traits>
using namespace __gnu_pbds;
using namespace std;
#define fasterthanlight cin.tie(0); ios::sync_with_stdio(0);
#define ll long long
#define lll __int128 
const ll inf = 1e9 + 7;
const ll inf2 = 1e9 + 9;
const ll inff= 998244353;
const ll infh = (1LL << 61) - 1;
#define pll pair<ll,ll>
#define pii pair<int,int>
#define vi vector<int>
#define vll vector<ll>
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define pb push_back
#define f0(i,n) for (int i=0;i<n;i++)
#define f1(i,n) for (int i=1;i<=n;i++)
#define ff0(i,n) for (int i=n-1;i>-1;i--)
#define ff1(i,n) for (int i=n;i>0;i--)
#define fs(i,a,b) for (int i=a;i<b;i++)
#define testcases int tzxhicjkha; cin>>tzxhicjkha;while (tzxhicjkha--)
#define usingfloats cout<<setprecision(20)
#define ineedtohash mll iqknabxiopk=1;for (ll iqknabxiop=0;iqknabxiop<HASHPOWMAX;iqknabxiop++){pows[iqknabxiop]=iqknabxiopk;iqknabxiopk*=B;}
#define sz(x) ((int)(x.size()))
template <class T> auto vect(const T& v, int n) { return vector<T>(n, v); }
template <class T, class... D> auto vect(const T& v, int n, D... m) {
  return vector<decltype(vect(v, m...))>(n, vect(v, m...));
}

//2*10^6 powers for hashing
const ll HASHPOWMAX=2000005;
int msb(int n)
{
	if (n==0){
		//cout<<"F";
		return 0;
	}
    int k = __builtin_clz(n);
 
    return 31 - k;
}
ll lmsb(ll n)
{
	if (n==0){
		//cout<<"F";
		return 0;
	}
    int k = __builtin_clzll(n);
 
    return 63 - k;
}
//I have no idea if the below code is safe or good
istream &operator>>(istream &is,__int128 &v) {
    string s;
    is>>s;
    v=0;
    for(auto &it:s) if(isdigit(it)) v=v*10+it-'0';
    if(s[0]=='-') v*=-1;
    return is;
}


ostream &operator<<(ostream &os,const __int128 &v) {
    if(v==0) return (os<<"0");
    __int128 num=v;
    if(v<0) os<<'-',num=-num;
    string s;
    for(;num>0;num/=10) s.pb((char)(num%10)+'0');
    reverse(all(s));
    return (os<<s);
}

/*
template<typename T, typename Q>ostream &operator<<(ostream &os,const pair<T,Q> &v) {
    return (os<<v.first<<" "<<v.second);
}
*/

//some cursed cin vector shit
template<typename T> istream &operator>>(istream &is,vector<T> &v) {
    for (T&i:v){
        is>>i;
    }
    return is;

}
template<typename T> ostream &operator<<(ostream &os,const vector<T> &v) {
    if (v.empty()){
        return os;
    }
    for (int i=0;i<v.size()-1;i++){
        os<<v[i]<<" ";
    }
    return os<<v[v.size()-1];
}

mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); 
//const ll B = 100;
const ll B = uniform_int_distribution<ll>(1000, inf - 1)(rng);

/*
//some cursed code
//allows int x=in;
struct {
	template<class T>
	operator T() {
		T x; std::cin >> x; return x;
	}
} in;
//breaks if string
//so do string s = (string)in;
*/

//ty Mark for modint code that I will change
template<long long MOD>
struct ModInt {
    long long v;
    ModInt() {
        v=0;
    }
    ModInt(long long _v) {
        v = _v % MOD;
        if (v < 0) {
            v += MOD;
        }
    }
 
    friend ModInt pow(ModInt base, long long exp) {
        ModInt res = 1;
        while (exp) {
            if (exp & 1) {
                res *= base;
            }
            base *= base;
            exp >>= 1;
        }
        return res;
    }
 
    ModInt &operator+=(ModInt b) {
        if ((v += b.v) >= MOD) {
            v -= MOD;
        }
        return *this;
    }
 
    ModInt &operator-=(ModInt b) {
        if ((v -= b.v) < 0) {
            v += MOD;
        }
        return *this;
    }
 
    ModInt &operator*=(ModInt b) {
        if constexpr (MOD==infh){
            //UNSAFE CODE PROBABLY
            uint64_t l1 = uint32_t(v), h1 = v >> 32;
            uint64_t l2 = uint32_t(b.v), h2 = b.v >> 32;
            uint64_t l = l1 * l2, m = l1 * h2 + l2 * h1, h = h1 * h2;
            uint64_t ret = (l & MOD) + (l >> 61) + (h << 3) + (m >> 29) + (m << 35 >> 3) + 1;
            ret = (ret & MOD) + (ret >> 61);
            ret = (ret & MOD) + (ret >> 61);
            v = ret - 1;
            return *this;
        }
        else if constexpr (MOD<=INT_MAX){
            //if less than or equal to INT_MAX, lll isn't needed
            v=v * b.v % MOD;
            return *this;
        }
        else{
            v = (__int128)1 * v * b.v % MOD;
            return *this;
        }
    }

	//division is scuffed
    ModInt &operator/=(ModInt b) {
        *this *= pow(b, MOD - 2);
        return *this;
    }
 
    friend ModInt operator+(ModInt a, ModInt b) {
        return a += b;
    }
 
    friend ModInt operator-(ModInt a, ModInt b) {
        return a -= b;
    }
 
    friend ModInt operator*(ModInt a, ModInt b) {
        return a *= b;
    }
 
    friend ModInt operator/(ModInt a, ModInt b) {
        return a /= b;
    }
    
    friend istream &operator>>(istream &is, ModInt &a) {
        long long x;
        is >> x;
        a = ModInt(x);
        return is;
    }
 
    friend ostream &operator<<(ostream &os, ModInt a) {
        return os << a.v;
    }

    bool operator==(const ModInt& y) const{
        return v == y.v;
    }

    bool operator!=(const ModInt& y) const{
        return v != y.v;
    }
    ModInt& operator++() {
        v++;
        if (v == MOD) v = 0;
        return *this;
    }
    ModInt& operator--() {
        if (v == 0) v = MOD;
        v--;
        return *this;
    }
    ModInt operator++(int) {
        ModInt result = *this;
        ++*this;
        return result;
    }
    ModInt operator--(int) {
        ModInt result = *this;
        --*this;
        return result;
    }
    //bad operators for completeness sake
    bool operator>(const ModInt& y) const{
        return v > y.v;
    }
    bool operator>=(const ModInt& y) const{
        return v >= y.v;
    }
    bool operator<=(const ModInt& y) const{
        return v <= y.v;
    }
    bool operator<(const ModInt& y) const{
        return v < y.v;
    }

};
using mll = ModInt<infh>;
using mint = ModInt<inf>;
using minf = ModInt<inff>;
	


ll exp(ll x, ll n, ll m=inf) {
	assert(n >= 0);
	x %= m;  // note: m * m must be less than 2^63 to avoid ll overflow
	ll res = 1;
	while (n > 0) {
		if (n % 2 == 1) { res = res * x % m; }
		x = x * x % m;
		n /= 2;
	}
	return res;
}
ll expu(ll x, ll n) {
	assert(n >= 0);
	ll res = 1;
	while (n > 0) {
		if (n % 2 == 1) { res = res * x; }
		x = x * x;
		n /= 2;
	}
	return res;
}
mll exph(mll base, ll exp) {
    mll res = 1;
    while (exp) {
        if (exp & 1) {
            res *= base;
        }
        base *= base;
        exp >>= 1;
    }
    return res;
}
minf expf(minf base, ll exp) {
    minf res = 1;
    while (exp) {
        if (exp & 1) {
            res *= base;
        }
        base *= base;
        exp >>= 1;
    }
    return res;
}
mint expo(mint base, ll exp) {
    mint res = 1;
    while (exp) {
        if (exp & 1) {
            res *= base;
        }
        base *= base;
        exp >>= 1;
    }
    return res;
}
vector<mll> pows(HASHPOWMAX);
const mll HMODINV=exph(B,infh-2);
struct hashPart {
    mll value;
    int len;
    hashPart() {
        value=0;
        len=0;
    }
    hashPart(mll x, int y) : value(x), len(y) {}
    hashPart operator+=(hashPart b) {
        hashPart a=hashPart(value * pows[b.len] + b.value, len + b.len);
        (*this).value=a.value;
        (*this).len=a.len;
        return *this;
    }
    hashPart operator+(hashPart b) {
        return hashPart(value * pows[b.len] + b.value, len + b.len);
    }
 
    bool operator==(hashPart b) {
        return value == b.value;
    }
};
template<class T>
struct hashString {
    vector<mll> hash;
 
    hashString(T s) {
        hash.resize(int(s.size()) + 1);
        for (int i = 0; i < int(s.size()); i++) {
            hash[i + 1] = (hash[i] * B + s[i]);
        }
        while (int(pows.size()) < int(hash.size())) {
            pows.push_back(pows.back() * B);
        }
    }
 
    hashPart getHash(int l, int r) {
        return hashPart(hash[r] -hash[l] * pows[r - l], r - l);
    }
 
    hashPart getHash() {
        return getHash(0, hash.size() - 1);
    }
};


//I don't understand the below code, all I know is it's good for hashing apparently
struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
ll es(ll x1, ll y1, ll x2, ll y2){
	return (x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
}
ll man(ll x1, ll y1, ll x2, ll y2){
	return abs(x1-x2)+abs(y1-y2);	
}



minf choose(int n,int k){
    if (k>n){
        return 0;
    }
    minf ret=1;
    for (int i=n;i>n-k;i--){
        ret*=i;
    }
    for (int i=1;i<=k;i++){
        ret/=i;
    }
    return ret;
}
//stolen from geeks for geeks
vector<int> sieve(int n)
{
    // Create a boolean array "prime[0..n]" and initialize
    // all entries it as true. A value in prime[i] will
    // finally be false if i is Not a prime, else true.
    bool prime[n + 1];
    memset(prime, true, sizeof(prime));
 
    for (int p = 2; p * p <= n; p++) {
        // If prime[p] is not changed, then it is a prime
        if (prime[p] == true) {
            // Update all multiples of p greater than or
            // equal to the square of it numbers which are
            // multiple of p and are less than p^2 are
            // already been marked.
            for (int i = p * p; i <= n; i += p)
                prime[i] = false;
        }
    }
    vector<int> ret;
    // Print all prime numbers
    for (int p = 2; p <= n; p++)
        if (prime[p])
            ret.pb(p);
    return ret;
}


void setup(){

}

typedef tree<double,null_type,less_equal<double>,rb_tree_tag,tree_order_statistics_node_update> indexed_set;



void solve(){
    ll s=0;
    for (int i=0;i<5;i++){
        ll a,b;
        cin>>a>>b;
        s+=a*b;
    }
    s/=5;
    ll c;
    cin>>c;
    s*=c;
    ll d;
    cin>>d;
    s/=d;
    cout<<s<<"\n";


}

signed main() {
    setup();
    //usingfloats;
	fasterthanlight;
	//ineedtohash;
    //testcases{
        solve();
    //}


}