#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <algorithm>
#include <deque>
#include <climits>
#include <cmath>
#include <numeric>
#include <string>
#include <bitset>
#include <assert.h>
#include <iomanip>
using namespace std;
 
template <typename T>
using pqg = priority_queue<T, vector<T>, greater<T>>;
 
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
 
template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
 
 
const long long infl = 1e18 + 1;
const int inf = 1e9 + 1;
const int mod1 = 1e9 + 7;
const int mod2 = 998244353;
const long double eps = 1e-7;
const int mod = mod1;
 
int add(int a, int b) { return (a + b) % mod; }
int sub(int a, int b) { return (a - b + mod) % mod; }
int mul(int a, int b) { return (int)((long long)a * b % mod); }
int pwr(int a, int b = mod - 2)
{
	int res = 1;
	for(; b > 0; b >>= 1, a = mul(a, a))
		if(b & 1)
			res = mul(res, a);
	return res;
}
 
void solve()
{
	int n;
	cin >> n;
	vector<pair<int, int>> a(n);
	for(auto &[f, s]: a)
		cin >> f >> s;
	int move = 1 + a[0].first;
	int res = 0;
	for(int i = 0; i < n; i += move)
		res++;
	cout << res;
}
 
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
 
	int t = 1;
	// cin >> t;
 
	while (t--) {
		solve();
		cout << (t ? "\n" : "");
	}
}