下面是我写的代码，为什么提交时会WA的？  测试了下好像没有错。。

Problem Description
FatMouse prepared M pounds of cat food, ready to trade with the cats guarding the warehouse containing his favorite food, JavaBean.
The warehouse has N rooms. The i-th room contains J[i] pounds of JavaBeans and requires F[i] pounds of cat food. FatMouse does not have to trade for all the JavaBeans in the room, instead, he may get J[i]* a% pounds of JavaBeans if he pays F[i]* a% pounds of cat food. Here a is a real number. Now he is assigning this homework to you: tell him the maximum amount of JavaBeans he can obtain.

 
 
Input
The input consists of multiple test cases. Each test case begins with a line containing two non-negative integers M and N. Then N lines follow, each contains two non-negative integers J[i] and F[i] respectively. The last test case is followed by two -1's. All integers are not greater than 1000.

 
 
Output
For each test case, print in a single line a real number accurate up to 3 decimal places, which is the maximum amount of JavaBeans that FatMouse can obtain.

 
 
Sample Input
5 3
7 2
4 3
5 2
20 3
25 18
24 15
15 10
-1 -1

#include<stdio.h>
#include<stdlib.h>
#define N 1000+5
struct Jean{
    double J;
    double F;
    double Temp;
}jb[N];
int cmp(const void *a,const void *b)
{
    return (*(struct Jean *)a).Temp<(*(struct Jean *)b).Temp? 1:-1;   
}

int main()
{
    double M,total,temp;
    int i,n,index,j;
    struct Jean temp1;
    while(scanf("%lf%d",&M,&n)!=EOF&&M!=-1&&n!=-1)
    {
        total=0;
        for(i=0;i<n;i++)
            scanf("%lf%lf",&jb[i].J,&jb[i].F);
        for(i=0;i<n;i++)
            jb[i].Temp=jb[i].J/jb[i].F;
        qsort(jb,n,sizeof(jb[0]),cmp);
        i=0;
        while(M!=0.0)
        {
            if(jb[i].F>M)
            {
                total=total+M*jb[i].J/jb[i].F;
                M=0;
            }
            else
            {
                total=total+jb[i].J;
                M=M-jb[i].F;
            }
            i++;
        }
        printf("%.3f\n",total);
    }
    return 0;
}