AC

#include <bits/stdc++.h>
using namespace std;
map<char, int>mp;

int main() {
	string s;
	cin >> s;

	for (int i = 0; i < s.size(); i++)

		mp[s[i]]++;

	for (int i = 0; i < s.size(); i++)

		if (mp[s[i]] == 1) {
			cout << i;
			exit(0);
		}

	cout << -1;
	return 0;
}