Finding_Shoes.cpp

#include <bits/stdc++.h>
using namespace std;

int main() {
	// your code goes here  
	int t;
	cin>>t;
	while(t--){
	    int n,m;
	    cin>>n>>m;
	    if(m>n){
	        cout<<n<<endl;
	    }
	    else{
	        cout<<(n*2)-m<<endl;
	        
	    }
	    
	    
	}

}