#include <iostream>
int fact(int n) {
if (n <= 1) return 1;
return fact(n-1) * n;
}
int find_sum(int n) {
int sum = 0;
for(auto i = 1; i <= n; i += 2)
sum += fact(i);
return sum;
int main() {
int n;
std::cin >> n;
std::cout << find_sum(n) << std::endl;
return 0;
#include <iostream>
int fact(int n) {
if (n <= 1) return 1;
return fact(n-1) * n;
}
int find_sum(int n) {
int sum = 0;
for(auto i = 1; i <= n; i += 2)
sum += fact(i);
return sum;
}
int main() {
int n;
std::cin >> n;
std::cout << find_sum(n) << std::endl;
return 0;
}