#include <bits/stdc++.h>
using namespace std;

using ll = long long;
#define rep(i, n) for(int i = 0; i < n; i++)

int main() {
	int M, N;
	cin >> M >> N;
	double ans = N;
	ans /= 3;
	ans += M;
	cout << fixed << setprecision(12) << ans << endl;
}