#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define X first
#define Y second
#define ALL(v) v.begin(), v.end()
#define pb push_back
#define SZ(a) ((int)a.size())

string s;
map<array<int, 3>, bool> table;

bool dp(int l, int r, int k) {
    if (k < 0) return 0;
    if (l >= r) return 1;
    if (table.find({l, r, k}) != table.end())
        return table[{l, r, k}];
    int res = 0;
    if (s[l] == s[r] && dp(l + 1, r - 1, k)) res = 1;
    else if (dp(l + 1, r, k - 1)) res = 1;
    else if (dp(l, r - 1, k - 1)) res = 1;
    return table[{l, r, k}] = res;
}

int main() {
    ios::sync_with_stdio(0), cin.tie(0);
    cin >> s;
    for (int i = 0; i <= 3; ++i) {
        if (dp(0, SZ(s) - 1, i)) {
            cout << i << "\n";
            return 0;
        }
    }
    cout << "-1\n";
}