#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;

// 把字符串中的每个字符扔到向量数组中，排序，再计数
int main () {
    int ans = 1;
    string s;
    cin >> s;
    int len = s.size();
    vector<char> arr(len);
    for (int i = 0; i < len; ++i) {
        arr[i] = s[i];
    }
    sort(arr.begin(), arr.end());
    char temp = arr[0];
    for (int i = 1; i < len; ++i) {
        if (temp != arr[i]) {
            temp = arr[i];
            ans++;
        }
    }
    cout << ans << endl;
    return 0;
}