#include <iostream>
using namespace std;

/**
 * @Author: Robert Rośczak LO nr. 1 w Łodzi.
 * @Problem: Palinrom (pal)
 */

int main() {
    int res = 0;
    bool isNull = false;
    string a;
    cin >> a;
    for (int i = 0; i < a.length()/2; ++i) {
        if (a[i] != a[a.length()-i-1]) {
            int b = i, c = i;
            while (a[b] != a[a.length()-i-1]) {
                b++;
                if (b == a.length()-i-1) {
                    if (isNull) {
                        cout << -1;
                        return 0;
                    }
                    isNull = true;
                    b = a.length()-i-1;
                    c = a.length()/2;
                    i--;
                    break;
                }
            }
            for (int d = b; d > c;d--) {
                char g = a[d];
                a[d] = a[d-1];
                a[d-1] = g;
                res++;
            }
        }
    }
    cout << res;
    return 0;
}