CodeForces 651A（水题）

Friends are going to play console. They have two joysticks and only one charger for them. Initially first joystick is charged at a₁ percent and second one is charged at a₂ percent. You can connect charger to a joystick only at the beginning of each minute. In one minute joystick either discharges by 2 percent (if not connected to a charger) or charges by 1 percent (if connected to a charger).

Game continues while both joysticks have a positive charge. Hence, if at the beginning of minute some joystick is charged by 1 percent, it has to be connected to a charger, otherwise the game stops. If some joystick completely discharges (its charge turns to 0), the game also stops.

Determine the maximum number of minutes that game can last. It is prohibited to pause the game, i. e. at each moment both joysticks should be enabled. It is allowed for joystick to be charged by more than 100 percent.

Input

The first line of the input contains two positive integers a₁ and a₂ (1 ≤ a₁, a₂ ≤ 100), the initial charge level of first and second joystick respectively.

Output

Output the only integer, the maximum number of minutes that the game can last. Game continues until some joystick is discharged.

Sample Input

Input

3 5

Output

6

Input

4 4

Output

5

题意 两个游戏机，每分钟充电电量加1，不充电量减2，只能给一台游戏机充电（可交换），当其中一台电量为0则停在，求持续的分钟数

#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
    int a1,a2;
    while(cin>>a1>>a2)
    {
        if(a1<a2)
        {
            a2=a1+a2;
            a1=a2-a1;
            a2=a2-a1;
        }
        if(a1==1&&a2==1)
            cout<<0<<endl;
        int t=0;
        while(a1>0&&a2>0)
        {
            if(a2>a1)
            {
                a2=a2-2;
                a1=a1+1;
            }
            else
            {
                a1=a1-2;
                a2=a2+1;
            }
            t++;
        }
        cout<<t<<endl;
    }
    return 0;
}