#include <bits/stdc++.h>
using namespace std;

int dp[100009][7];
int Answer = (1 << 30);
string S;

void update(int cl, int cr, int v) {
    int val = cl + cr;
    val -= (int)(S.size() - 1);
    val += 3;
    if (0 <= val && val <= 6) dp[cl][val] = min(dp[cl][val], v);
}

int main() {
    // Step 1. Input
    cin >> S;

    // Step 2. DP Init
    for (int i = 0; i < S.size(); i++) {
        for (int j = 0; j < 7; j++) dp[i][j] = (1 << 30);
    }
    dp[0][3] = 0;

    // Step 3. DP
    for (int i = 0; i < (int)S.size(); i++) {
        for (int j = 6; j >= 0; j--) {
            if (dp[i][j] == (1 << 30)) continue;
            int cl = i;
            int cr = (S.size() - 1 - i); cr += (j - 3);
            // cout << i << " " << j << " " << cl << " " << cr << " " << dp[i][j] << endl;
            if (cr - cl == -1 || cr - cl == 0) {
                Answer = min(Answer, dp[i][j]);
            }
            if (cl >= 0 && cr < (int)S.size()) {
                if (S[cl] == S[cr]) update(cl + 1, cr - 1, dp[i][j]);
                update(cl + 1, cr, dp[i][j] + 1);
                update(cl, cr - 1, dp[i][j] + 1);
            }
        }
    }

    // Step 4. Get Answer
    if (Answer >= 4) cout << "-1" << endl;
    else cout << Answer << endl;
    return 0;
}