#include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define Would #define you const int INF = 999999999; const int MOD = 1e9 + 7; const double pi = 3.141592653589793238; int a, b, ans; int main() { cin >> a >> b; for (int i = a; i <= b; ++i) { if ((a + b + i) % 3 == 0) { ++ans; } } cout << ans << endl; }