#include<bits/stdc++.h>
#define ULL unsigned long long
#define int long long
#define endl '\n'
#define debug(a) cout<<#a<<"="<<a<<endl;
#define all(v) v.begin(), v.end()
#define PII pair<int,int>
using namespace std;
constexpr int N =  1 *1e6 + 10,M = 5 * 1e3 + 10,inf = 0x3f3f3f3f;


void solve()
{
    string str;
    cin >> str;
    sort(all(str));
    str.erase(unique(all(str)),str.end());
    cout<<str.size()<<endl;
}
signed main()
{
    ios::sync_with_stdio(0);cin.tie(nullptr),cout.tie(nullptr);
    int _=1;
    // cin>>_;
    while(_--)
    {
        solve();
    }
    return 0;
}

/**
 *    author: Nijika_jia
 *    created: 2024.10.23 10:33:03
 */