#include <stdio.h>
void swap (int *n,int *m);
void swap2 (double *n,double *m);
int main ()
{
	int i,m,k,t,n;
	double sum = 0;
	int arr[110]={0},brr[110]={0};
	double crr[110]={0};
	scanf ("%d%d",&n,&t);
	for (i = 0;i<n;i++)
	{
		scanf ("%d%d",&arr[i],&brr[i]);
		crr[i]= (double)brr[i]/(double)arr[i];
	}
	for (i = 0;i<n-1;i++)
	{
		for (k = 0;k<m-i-1;k++)
		{
			if (crr[k]<crr[k+1])
			{
				swap2 (&crr[k],&crr[k+1]);
				swap (&arr[k],&arr[k+1]);
				swap (&brr[k],&brr[k+1]);
			}
		}
	}
	for (i = 0;i<n;i++)
	{
		if ((t-arr[i])>0)
		{
			sum += brr[i];
			t -= arr[i];
		}
		else
		{
			sum += t*crr[i];
			break;
		}
	}
	printf ("%.2f",sum);
	return 0 ;
} 
void swap (int *n,int *m)
{
	int temp;
	temp = *n;
	*n = *m;
	*m = temp;
	return;
}
void swap2 (double *n,double *m)
{
	double temp;
	temp = *n;
	*n = *m;
	*m = temp;
	return;
}

求大佬帮忙看看哪有问题，自己测试样例是对的，可是交上去全WA_(:з」∠)_