代码如下```cpp

#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;
int n,t,point=1;
float sum;
struct g
{
	int m,v;
	float p;
}gold[101];
bool pp(g x,g y)
{
	return x.p>y.p;
}
int main()
{
	scanf("%d%d",&n,&t);
	for(int i=1;i<=n;i++)
	{
		scanf("%d%d",&gold[i].m,&gold[i].v);
		gold[i].p=float(gold[i].v)/float(gold[i].m);
	}
	sort(gold+1,gold+n,pp);
	while(t-gold[point].m>=0)
	{
		t=t-gold[point].m;
		sum+=gold[point].v;
		point++;
	}
	sum+=gold[point].p*t;
	printf("%.2f\n",sum);
	return 0;
}