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