#include<bits/stdc++.h>
using namespace std;
#define ll long long
const ll inf=2e9;
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	int t;cin>>t;
	while(t--) {
		ll x,y,z;
		cin>>x>>y>>z;
		ll ori=x;
		x+=y;
		if(x<z) {
			cout<<"-1\n";
		}
		else if(x==z) {
			cout<<inf<<"\n";
		}
		else {
			ll cha=x-z;
			if(cha<=z) {
				cout<<"-1\n";
			}
			else {
				if(ori>=cha) {
					cout<<"-1\n";
				}
				else {
					cout<<cha<<"\n";
				}
			}
		}
	}
}