初学者：学c之前学了一周java，用java方法写c总是不能出来正确结果

#include <stdio.h>
void main()
{
    int num;
    int sum=0;
    int count =0;
    scanf("%d",&num);
        while(num!=-1){
        sum+=num;
        count++;
        scanf("%d",&num);
        }
    if(count!=0)printf("=%d\n",(double)sum/count);
    return 0;
}