#include <iostream>
#include <unordered_map>
#include <unordered_set>
using namespace std;

int main() {
    unordered_set<char> set;
    string s;
    cin >> s;
    for(auto x : s){
        set.insert(x);
    }
    int count = 0;
    for(auto cut : set)  count++;
    cout << count << endl;
    }