#include<iostream>
using namespace std;
int n,a[105],p[55];
void cj(int a,int b)
{
	int s;
	if(b < 16)s = a - 10;
	else if(b > 20)s = a -(b-20);
	else s = a;
	if(s<0)cout<<0<<endl;
	else cout<<s<<endl;
}
int main()
{
	
	cin>>n;
	for(int i = 0;i<n;i++)cin>>a[i]>>p[i];
	for(int i = 0;i<n;i++)
	{
		cj(a[i],p[i]);		
	}
	return 0;
}