#include<stdio.h>
long long function(int num){
    long long fact = 1;
    for (int i = 1; i <= num; i++){
        fact *= i;
    }
    return fact;
}
int main(){
    int n;
    scanf("%d", &n);
    if (n <= 0){
        printf("Invalid Input");
        return 0;
    }
    long long result = 0;
    for (int i = 1; i <= n; i++){
        if(i % 2 != 0)
            result += function(i);
        else
            result -= factorial(i);
    }
    printf("%lld", result);
    return 0;
}