#include<bits/stdc++.h>
using namespace std;
#define int long long
void solve()
{
	int x, y, z;
	std:: cin >> x >> y >> z;
	int t = x + y;
	if(t < z)
	{
		std:: cout << -1 << endl;
		return ;
	}
	else if(t == z)
	{
		std:: cout << z + 1 << endl;
	}
	else
	{
		int ans = t - z;
		if(ans <= z)
		{
			std:: cout << -1 << endl;
			return ;
		}
		else
		{
			if(t - z <= x)
			{
				std:: cout << -1 << endl;
				return ;
			}
			std:: cout << t - z << endl;			
		}
	}
}   
signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
    int T;
    std:: cin >> T;
    while(T -- )
	solve();
	return 0;
}