#include <iostream>
using namespace std;

int main()
{
    
    
    
    bool hash[128] = {
    
     false };
    string s;
    cin >> s;
    int m=0;
    for (int i = 0; i<s.length(); i++)
    {
    
    
        m = (int)s[i];
        hash[m] = true;
    }
    
    int num = 0;
    for (int i = 0; i < 128; i++)
    {
    
    
        if (hash[i] == true)
            num++;
    }
    cout << num << endl;

    return 0;
}