#include"bits/stdc++.h"
#include"ext/pb_ds/tree_policy.hpp"
#include"ext/pb_ds/assoc_container.hpp"
using namespace std;
using namespace __gnu_pbds;
#define FOR(i,a,b)for(int i=a;i<b;i++)
#define F0R(i,a)FOR(i,0,a)
#define ROF(i,a,b)for(int i=b-1;a<=i;i--)
#define R0F(i,a)ROF(i,0,a)
#define rep(a)F0R(_,a)
#define each(a,x)for(auto&a:x)
#define all(a)begin(a),end(a)
#define sz(x)int(size(x))
#define lla(x)rbegin(x),rend(x)
#define SUM(a)accumulate(all(a),0ll)
#define SUMM(a,b)accumulate(a,a+b,0ll)
#define MAX(a)*max_element(all(a))
#define MAXX(a,b)*max_element(a,a+b)
#define MIN(a)*min_element(all(a))
#define MINN(a,b)*min_element(a,a+b)
#define con const int
#define lwb lower_bound
#define upb upper_bound
#define bry binary_search
#ifdef LOCAL
#define print(x)cout<<x;
#else
#define print(...)
#endif
#define debug(x)print(#x<<" = "<<x<<endl)
using ld=long double;
using ll=long long;
using str=string;
template<class T>using oset=tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
template<class T>using omset=tree<T,null_type,less_equal<T>,rb_tree_tag,tree_order_statistics_node_update>;
template<class T>T minn(T a){return a;}
template<class T,class...Args>T minn(T a,Args... args){return min(a,minn(args...));}
template<class T>T maxx(T a){return a;}
template<class T,class...Args>T maxx(T a,Args... args){return max(a,maxx(args...));}
#define SMIN(a,b...)a=min(a,minn(b))
#define SMAX(a,b...)a=max(a,maxx(b))
void fileset(str a){assert(nullptr!=freopen((a+".in").c_str(),"r",stdin)&&nullptr!=freopen((a+".out").c_str(),"w",stdout));}
int main(){
    int N;
    cin >> N;

    int l = 0;

    rep (2 * N){
        cin >> l;
    }

    cout << (N + l) / (l + 1) << endl;
}