rt

Code:

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int MAXN = 1e5 + 100;
ll n, k, L, R, h[MAXN], w[MAXN];
bool checker(int x){
	ll sum = 0;
	for(int i = 1; i <= n; i++){
		sum += ((h[i] / x) * (w[i] / x));
	}
	return sum >= k;
}
int main(){
	cin >> n >> k;
	for(int i = 1; i <= n; i++){
		cin >> h[i] >> w[i];
		R = max(R, max(h[i], w[i]));
	}
	L = 1;
	while(L < R){
		ll mid = (L + R) / 2;
		if(checker(mid)) L = mid + 1;
		else R = mid;
	}
	cout << L - 1 << endl;
	return 0;
}