> #include<stdio.h>
> int main()
> {
>     int i;
>     float month[11];//要用double型float不够精确
>     float  m=0.00;
>     for(i=0;i<=3;i++)
>     { 
> 	scanf("%f",&month[i]);
> 	m=month[i]+m;
>     }
>     printf("$%.2f\n",m/12);
> }
#include <stdio.h>
void main()
{
	double  sum=0,num;
	int i;
	for(i=0;i<12;i++)
	{
		scanf("%lf",&num);
		sum+=num;
	}
	printf("$%.2f\n",sum/12);
}