#include <vector>
#include <iostream>
#include <fstream>
#include <set>
#include <algorithm>
#include <map>
#include <list>
#include <string>
#include <ctime>
#include <random>
#include <stack>
#include <iomanip>
#include <deque>
#include <queue>
#include <ctime>
#include <bitset>
#include <fstream>

using namespace std;
typedef long long ll;
const long long inf = 2e9;
const long long mod = 1e9 + 7;

string s, r;
int n;
vector<ll>pr;
vector<ll>po;
ll b = 31;

long long get_hash(int pos) {
	return (pr[pos + n] - (pr[pos] * po[n]) % mod + mod) % mod;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> s;
	r = s;
	n = s.size();
	reverse(r.begin(), r.end());
	s += s;
	pr.resize(2 * n + 1);
	po.resize(2 * n + 1);
	po[0] = 1;
	for (int i = 1; i <= 2 * n; i++) {
		po[i] = po[i - 1] * b;
		po[i] %= mod;
	}
	for (int i = 1; i <= n * 2; i++) {
		pr[i] = (pr[i - 1] * b + (s[i - 1] - 'a' + 1)) % mod;
	}
	ll ch = 0;
	ll t = 1;
	for (int i = 1; i <= n; i++) {
		ch += (po[n-i] * (r[i - 1] - 'a' + 1)) % mod;
		ch %= mod;
	}
	for (int i = 0; i < n; i++) {
		if (get_hash(i) == ch) {
			cout << i;
			system("pause>nul");
			return 0;
		}
	}
	cout << -1;
	//system("pause>nul");
	return 0;
}