#include<bits/stdc++.h>
#define WR "txt"

void Open() { freopen(WR".in", "r", stdin); freopen(WR".out", "w", stdout); }
void Close() { fclose(stdin); fclose(stdout); }
using namespace std;
int Read()  {
	int val = 0, opt = 1; char ch;
	while (!isdigit(ch = getchar() )) if (ch == '-') opt = -1;
	while (isdigit( ch )) (val *= 10) += ch - '0', ch= getchar();
	return val * opt;
}

void work()  {
	printf("%d", (Read() * 3 + Read()) / 2);
}

int main(void)  {
	//Open();
	work();
	//Close();
	return 0;
}