#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <string>
using namespace std;

#define MAX(a,b) ((a)>(b)?(a):(b))
#define MIN(a,b) ((a)<(b)?(a):(b))
#define ABS(a) ((a)>(0)?(a):-(a))
#define rep(i,a,b) for(int (i)=int(a);(i)<int(b);(i)++)
#define rrep(i,a,b) for(int (i)=int(a);(i)>=int(b);(i)--)

#define put(a) cout << (a) << endl

#define INF 1000000001
#define MOD 1000000007
#define INF64 1000000000000000001

#define F first
#define S second

#define Pii  pair<int,int>
#define Pll  pair<long long,long long>
#define Piii pair<int,pair<int,int>>
#define Plll pair<long long,pair<long long,long long>>

#define Vll(a,b,c)    vector<vector<long long>> (a)((b),vector<long long>((c))
#define Vlll(a,b,c,d) vector<vector<vector<long long>>> (a)((b),vector<vector<long long>>((c),vector<long long>((d)))

#define MAX_N 1000000
int N,M,L;
int K[MAX_N];
int ans;
vector<char> C;
bool bool_ans;

int solve(void) {

  ans = (A * 3 + P)/ 2;
  return ans;
}

int main (void)
{
  cin >> N >> M;

  ans = solve();
  put(ans);

  return 0;
}
