anagram.cpp

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

void solve()
{
    string s;
    cin >> s;
    
    int n = s.size();
    
    if ( n&1 ) cout << -1 << endl;
    else {
        int h1[26], h2[26];
        
        for ( int i = 0; i < 26; i++ ) h1[i] = h2[i] = 0;
        
        for ( int i = 0; i < n/2; i++ ) {
            h1[s[i]-'a']++;
            h2[s[(n/2)+i]-'a']++;
        }
        
        int ans = 0;
        for ( int i = 0; i < 26; i++ ) ans += abs( h1[i]-h2[i]);
        
        ans >>= 1;
        cout << ans << endl;
    }
}

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    int testcase;
    cin >> testcase;
    
    for ( int t = 1; t <= testcase; t++ ) {
        solve();
    }
    
    return 0;
}