lacko

#include <stdio.h>  int main ()    {int a=0,b=0,sum=0,kredit=0;             while (scanf("%d,%d",&a,&b) && a,b !=0)       {if (b!=1)          sum+=a*b;          kredit+=a;        else          kredit+=a;               }        printf("%.2f",(float)sum/kredit);     }