#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main(){
    ll n,m;
    cin >> n >> m;
    vector<ll>c(n);
    rep(i,n){
        ll a,b;
        cin >> a >> b;
        c[i] = (m-a)/b;
    }
    sort(c.begin(),c.end());
    ll l=0,r=n+1;
    while(l+1!=r){
        int x=(l+r)/2;
        bool ok=true;
        rep(i,n){
            if(i/x>c[i])ok=false;
        }
        if(ok)r=x;
        else l=x;
    }
    cout << r << endl;
    return 0;
}