#include<iostream>
 
using namespace std;
 
void aa(int n, int& sum){
 
	if(n == 0){
	cout << n << "!= " << sum << endl;


	}

	else{
    aa(n-1, sum);  
	sum = sum*n ;  
	cout << n << "!= " << sum << endl;
        }
 
}
 
int main(){
	int a =6 ;
    int sum = 1;     
	aa(a, sum);
        return 0;
 
}