#include <iostream>
#include <string>
using namespace std;
int firstUniqChar(string s) {
	int count[128] = {0};
	for (char c : s) {
    	count[c]++;
	}
	for (int i = 0; i < s.size(); ++i) {
    	if (count[s[i]] == 1) {
        	return i;
    	}
	}
	return -1;
}

int main() {
	string s;
	cin >> s;
	cout << firstUniqChar(s) << endl;
	return 0;
}