#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define rep(i,n) for(int i=0;i<(int)(n);++i)

int main(){
    int N,M;
    cin>>N>>M;
    vector<int> A(N);
    rep(i,N){
        int a,b;
        cin>>a>>b;
        A[i]=(M-a)/b;
    }
    sort(all(A));
    int ans=0;
    rep(i,N){
        ans=max(ans,(i+A[i]+1)/(A[i]+1));
    }
    cout<<ans<<"\n";
}