Why is it wrong?(不想调了，麻烦各位大佬帮忙揪一下错误

#include<bits/stdc++.h>
using namespace std;
struct s{
	int a,b;
	double c;
}z[105];
bool cmp(s d,s e){
	return d.c<e.c;
}
int main(){
    int t,m,sum=0;cin>>t>>m; 
    for (int i=1;i<=m;i++){
    	cin>>z[i].a>>z[i].b;
    	z[i].c=z[i].a*1.0/z[i].b;
	}
	sort(z+1,z+1+m,cmp);
	for (int i=1;i<=m;i++){
		if(t>=z[i].a)sum+=z[i].b,t-=z[i].a;
		if(t<=0)break;
	}
	cout<<sum;
	return 0;
}