#include <iostream>
int main() {
    int n;
    std::cin >> n;
    int matchsticks = n * 3;
    std::cout << matchsticks;
    return 0;
}    
/**************************************************************
	Problem: 1596
	User: fuyijun
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/