#iclude<stdio.h>
int factorial(int n){
    if(n==0)return 1;
    else return n*factorial(n-1);
    
}
int main(){
    int n;
    scanf("%d",&n);
    
    if (n<0 ||n>10){
        printf("Invalid Input\n");
    }else{
        printf(%d\n",factorial(n));
        
    }    
    return 0;
}