#include<bits/stdc++.h>

using namespace std;

const int N = 1e5+5;
const int M = 5e4 + 10;
typedef long long ll;
typedef double db;
typedef pair<int, int>pii;
typedef pair<long, long>pll;
int dx[4] = { 0, 1, 0, -1 }, dy[4] = { 1, 0, -1, 0 };

inline long long read()
{
	long long w = 1;
	long long q = 0;
	char ch = ' ';
	while (ch != '-' && (ch < '0' || ch>'9')) ch = getchar();
	if (ch == '-') w = -1, ch = getchar();
	while (ch >= '0' && ch <= '9')
		q = q * 10 + ch - '0', ch = getchar();
	return w * q;
}
void solve()
{
	int x, y, z;
	cin >> x >> y >> z;
	int sum = x + y - z;
	if (sum < 0)
	{
		cout << -1 << endl;
		return;

	}
	else
	{
		cout << sum << endl;
		return;
	}
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int tcase = 1;
	cin >> tcase;
	while (tcase--)
		solve();
	return 0;

}