Accepted
/in/foo.c: In function 'main':
/in/foo.c:2:5: warning: type of 'undisign' defaults to 'int' [-Wimplicit-int]
 int main(undisign)  
     ^~~~
  代码
#include <stdio.h>  
int main(undisign)  
{  
	int i;
	int a=1;
	int num=1;
    scanf("%d", &a);
    for(i=1; i<=a; i++) 
    { 
        num *= i; 
    } 
    printf("%d\n",num); 
	return 0;  
}