#include<stdio.h>intmain(){
int number;
int sum = 0;
int count = 0;
double mean;
scanf_s("%d", &number);#visual studio中输入为scanf_swhile (number != -1) {
sum = sum + number;
count++;
scanf_s("%d", &number);
}
mean = sum / count;
printf("%f", mean);
return0;
}