#include <stdio.h>
long long factorial(int num) {
    if (num < 0) {
        return 0;
    }
    long long fact = 1;
    for (int i = 1; i <= num; i++) {
        fact *= i;
    }
    return fact;
}
    int main() {
        int n;
        long long total_clash_power = 0;
        scanf("%d", &n);
        if (n <= 0) {
            printf("Invalid input\n");
            return 0;
        }
        for (int i = 1; i <= n; i++) {
            if (i % 2 != 0) {
                total_clash_power += factorial(i);
            } else {
                total_clash_power -= factorial(i);
            }
        }
        printf("%11d\n", total_clash_power);
        return 0;
}