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. 

 

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. 

 

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. 

 

 

 

 #include<iostream>

 #include<cstring>

 #include<cstdio>

 #include<algorithm>

 using namespace std;

 int main()

 {

     int m,n;

     int f[],j[];

     double a[],b[];

     int next[];

     while((scanf("%d%d",&m,&n)&&(m!=-||n!=-)))

     {

         for(int i=;i<n;i++)

         {

             scanf("%d%d",&f[i],&j[i]);

             a[i]=1.0*f[i]/j[i];

         }

         double num=;

         for(int i=;i<n;i++)

         {

             for(int k=i+;k<n;k++)

             {

                 if(a[i]<a[k])

                 {

                     swap(a[i],a[k]);

                     swap(f[i],f[k]);

                     swap(j[i],j[k]);

                 }

             }

             if(j[i]<m)

             {

                 num+=f[i];

                 m-=j[i];

             }

             else

             {

                 num+=1.0*f[i]*m/j[i];

                 m=;

             }

             if(m==)

             {

                 break;

             }

         }

         printf("%.3lf\n",num);

     }

 }