#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
int main() {
char s[101];
cin >> s;
sort( s, s + strlen(s) );
int k = 1;
char c = s[0];
for(int i = 0; i < strlen(s); i++){
if( s[i] != c ){
c = s[i];
k++;
}
}
cout << k;
return 0;
}
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