#define _USE_MATH_DEFINES #define _CRT_SECURE_NO_WARNINGS #include<stdio.h> #include<string> #include<iostream> #include<iostream> #include<cctype> #include<cstdio> #include<vector> #include<stack> #include<queue> #include <algorithm> #include<math.h> #include<set> #include<map> #include <sstream> #include<iomanip> #include <ctype.h> using namespace std; //#include<bits/stdc++.h> int main() { int a, b; cin >> a >> b; int ans = 0; for (int i = a; i <= b; i++) { if ((a + b + i) % 3 == 0)ans++; } cout << ans << endl; return 0; }