请兄弟们帮我看看下面哪里出错了,我都快闷死了
/* Note:Your choice is C IDE */
#include "stdio.h"
main()
{
int a,b;
int su(int x);
scanf("%d",&a);
b=su(int a);
if(b==0)printf("%d isn't sushu",a);
else printf("%d is sushu",a);
}
int su(int a)
{int m,n;
if(a<4)n=1;
for(m=2;m<a;m++);
{