#include"stdio.h"

main()
{
double ave;
int data;
int num=0;
double sum=0;

printf("to terminate input ^D\n");

printf("data=");
while(scanf("%d",&data) !=EOF)
{
sum+=data;
num++;
printf("data=");
}

if(num==0)
printf("can't calculate the average\n");
else
{
ave=sum/num;
printf("the average of %d data is %f\n",num,ave);
}
}