就是根据题目的意思来的啊。为什么会全WA啊？

#include<bits/stdc++.h>
using namespace std;
const int N = 1e6+5;
int n;
int minn = INT_MAX,maxtime = INT_MIN;
struct node{
	int use,last;
}a[N];
bool cmp(node x,node y){
	if(x.use==y.use)return x.last<y.last;
	return x.use<y.use;
}
int main(){
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i].use>>a[i].last;
		minn = min(minn,a[i].last);
	}
	sort(a+1,a+1+n,cmp);
	if(a[1].use>a[1].last){
		cout<<"-1";
		return 0;
	}
	if(a[1].use==a[1].last){
		cout<<"1";
		return 0;
	}
	for(int i=1;i<=minn;i++){
		int now=a[1].use;
		bool flag=0;
		for(int j=2;j<=n;j++){
			now+=a[i].use;
			if(now>a[i].last){
				flag=1;
				break;
			}
		}
		if(flag==0){
			maxtime = max(maxtime,i);
		}
	}
	cout<<maxtime;
	return 0;
}