cf 1560B

#include<bits\stdc++.h>

using namespace std;

int main()
{
    int t;
    scanf("%d", &t);

    while(t--)
    {
        long long a, b, c;
        scanf("%lld %lld %lld", &a, &b, &c);

        int n = 2*abs(a-b) ;
        if(a > n || b > n || c > n) printf("-1\n");
        else
        {
            c += n/2;
            while(c > n) c -= n;
            printf("%lld\n", c);
        }
    }

}