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

const int MAX = 1e5 + 7;
int N;
string str;

map<pair<int, int>, bool> mp[MAX];

bool is_palin(int i, int j, int k) {
	if (k < 0)
		return false;
	if (i == j or i - j == 1)
		return true;
	if (i > j)
		return false;

	auto tmp = mp[i].insert(make_pair(make_pair(j, k), false));
	bool &res = tmp.first->second;
	if (tmp.second == false)
		return res;
	
	res = false;
	if (str[i] == str[j])
		res |= is_palin(i + 1, j - 1, k);

	if (k > 0) {
		res |= is_palin(i + 1, j, k - 1);
		res |= is_palin(i, j - 1, k - 1);
	}
	
	return res;
}
	
int main(void) {
	ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	cin >> str;
	N = str.size();

	for (int k = 0; k <= 3; k++)
		if (is_palin(0, N - 1, k)) {
			cout << k;
			return 0;
		}

	cout << -1;
	return 0;
}