#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001LL


int main(){
	
	int N,M;
	cin>>N>>M;
	
	vector<long long> a(N),b(N);
	vector<long long> t(N);
	rep(i,N){
		
		cin>>a[i]>>b[i];
		long long tt = M+1 - a[i];
		t[i] = (tt + b[i] - 1)/b[i];
	}
	sort(t.begin(),t.end());
	long long ok = N,ng = 0;
	while(ok-ng>1LL){
		long long mid = (ok+ng)/2;
		bool f = true;
		rep(i,N){
			if(mid*t[i]<i+1){
				f = false;
				break;
			}
		}
		if(f)ok = mid;
		else ng = mid;
		
	}
	cout<<ok<<endl;
	return 0;
}