Problem:
Score : 300 points

Problem Statement

Snuke loves puzzles.

Today, he is working on a puzzle using S- and c-shaped pieces.
In this puzzle, you can combine two c-shaped pieces into one S-shaped piece, as shown in the figure below:

Snuke decided to create as many Scc groups as possible by putting together one S-shaped piece and two c-shaped pieces.

Find the maximum number of Scc groups that can be created when Snuke has N S-shaped pieces and M c-shaped pieces.

Constraints

1 ≤ N,M ≤ 10^{12}

Input

The input is given from Standard Input in the following format:

N M

Output

Print the answer.

Sample Input 1

1 6

Sample Output 1

2

Two Scc groups can be created as follows:

Combine two c-shaped pieces into one S-shaped piece

Create two Scc groups, each from one S-shaped piece and two c-shaped pieces

Sample Input 2

12345 678901

Sample Output 2

175897

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
int main()
 
{
	//freopen("input.txt","r",stdin);
	//freopen("output.txt","w",stdout);
	long long int n,m,rem,msize=0;
	cin>>n >>m;
	if(n*2<=m)
	{
		rem=m-n*2;
	while(rem!=0)
	
		{  
			msize++;
			rem=rem-4;
		}

	cout<< msize+n;
	}
	else
	
	{
		m=m/2;
		msize=+m;
		cout<<msize;
	}
	
	

}