#include <bits/stdc++.h>   using namespace std;   using ll = long long;   int main() {     ll N, M;     cin >> N >> M;     if (N > M) swap(N, M);     ll rem = 0;     if (N == 1) {       rem = min(M % 6, 6 - M % 6);     } else {       if (N % 2 == 1 && M % 2 == 1) {         rem = 1;       } else {         if (M == 2) {           rem = 4;         } else if (M == 3 || M == 7) {           rem = 2;         } else {           rem = 0;         }       }     }     cout << N * M - rem << endl;     return 0;   }   