#include <stdio.h> int main () { int fac(int n); int n; int y; printf("input is numbren:"); scanf("%d",&n); y=fac(n); printf("%d! is %d\n",n,y); return 0; } int fac(int n) { int c; if(n==1||n==0) c=1; else c=n*fac(n-1); return c; }