#include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <sstream>

using namespace std;

#define rep(i, n) for (int i = 0; i < n; i++)
#define pri(a) cout << a << endl
#define pri2(a, b) cout << a << " " << b << endl
#define in(a) cin >> a
#define in2(a, b) cin >> a >> b
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>

typedef long long ll

//以上テンプレ

int main () {
    int a,p;
    in2(a, p);
    int s = (a * 3) / 2;
    pri(s);
}