#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

int main() {
	char s[101];
	cin >> s;
	sort( s, s + strlen(s) );
	int k = 1;
	char c = s[0];
	for(int i = 0; i < strlen(s); i++){
		if( s[i] != c ){
			c = s[i];
			k++;
		}
	}
	cout << k;
	return 0;
}