#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <algorithm>
#include <utility>
#include <map>
#include <set>
#include <string>
#include <cstring>
#include <queue>
#define rf freopen("in.in", "r", stdin)
#define wf freopen("out.out", "w", stdout)
#define rep(i, s, n) for(int i=int(s); i<=int(n); ++i)
using namespace std;
const int mx = 1e5 + 10, mod = 1e9+7;
int main()
{
//rf;// wf;
ios::sync_with_stdio(0);
int t; cin >> t;
while(t--)
{
string s;
cin >> s;
int n = s.size();
int cnt_a = 0, cnt_b = 0;
rep(i, 0, n-1)
{
cnt_a += (s[i] == 'A');
cnt_b += (s[i] == 'B');
}
if(cnt_a == 2)
{
cout << "A\n";
continue;
}
else if(cnt_b == 2)
{
cout << "B\n";
continue;
}
else if(n < 4)
{
cout << "-1\n";
continue;
}
string ans = "";
s = '.' + s + '.';
for(int i = 0; i <= n-2; ++i)
{
if(s[i+2] != s[i+3] and s[i+1] == s[i+2] and s[i] != s[i+1])
{
rep(j, 1, n)
{
if(j!=i+1)
ans += s[j];
}
break;
}
}
cout << ((ans == "")? "-1": ans) << endl;
}
return 0;
}
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