#include <stdio.h>
int factorial (int num) {
    int 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;
    }
    int result = 0;
    for (int i = 1; i <= n; i++) {
        if (i % 2 == 1) {
            result += factorial(i);
        }else {
            result _= factorial(i);
        }
    }
    printf("%d", result);
    return 0;
}