#include <iostream>
#include <string>

using namespace std;

int main() {
    string a; cin >> a;
    int i, j, k = 0;
    char d[10000];
    for (i = 1 ; i <= a.size() - 1 ; i+=3) {
    	for (j = 0 ; j < k ; i++) {
    		if (a[i] == d[j]) break;
    	}
    	if (j == k) {d[k] = a[i]; k++;}
    }
    cout << k - 1;
}