#include <bits/stdc++.h>
#define MOD 1000000007LL
using namespace std;
typedef long long ll;
typedef pair<int,int> P;

int n,d;
ll x[100005],v[100005];

int main(void){
	scanf("%d%d",&n,&d);
	ll sum=0;
	for(int i=0;i<n;i++){
		scanf("%lld%lld",&x[i],&v[i]);
		sum+=v[i];
	}
	printf("%lld\n",(d+sum-1LL)/sum);
	return 0;
}