#include <iostream>

int main() {
    int n;
    std::cin >> n;
    int matchsticks = 3 * n;
    std::cout << matchsticks << std::endl;
    return 0;
}    
/**************************************************************
	Problem: 1596
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/