【提问】c语言简单编程问题求解！！！！！

#include<stdio.h>
void main()
{
int m;
float ret;
printf("Enter students' number m:");
scanf("%d",&m);
ret=fact(m);
printf("average grade:%f",ret);
}
float ave(int n)
{
int i;
float grade,s=0,average;
for(i=1;i<=n;i++)
{
printf("input grade:");
scanf("%f",&grade);
s+=grade;
}
average=s/n;
return average;
}
跪求错哪儿了。。，

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