#include<iostream>
#include<cstring>
#include<algorithm>
#include<bits/stdc++.h>

using namespace std;
int N = 0,
	K = 0;
	
bool check(int side,vector<pair<int,int>>& list)
{
	int cnt = 0;
	
	for(int i = 0 ; i < list.size();i ++)
	{
		cnt += ((list[i].first / side) * (list[i].second / side));
		if(cnt >= K)
		{
			return true;
		}
	}
	
	return false;
}

int BinarySearchAns(vector<pair<int,int>>& list,int left,int right)
{
	while(left + 1 < right)
	{
		int mid = (left + right) >> 1;
		
		if(check(mid,list))
		{
			left = mid;
		}
		else
		{
			right = mid;
		}
	}
	
	return left;
}

int main(void)
{
	//二分答案
	
	vector<pair<int,int>> list;
	

	scanf("%d%d",&N,&K);
	
	int maxLen = -1;
	
	for(int i = 0 ; i < N ; i ++)
	{
		int h = 0,
			w = 0;
		scanf("%d%d",&h,&w);
		maxLen = max(maxLen,h);
		maxLen = max(maxLen,w);
		list.push_back({h,w});
	}
	
	int ans = BinarySearchAns(list,1,maxLen);
	
	printf("%d",ans);
	return 0;
}

疑问如题