import java.io.*;
import java.util.*;
public class Main{
public static void main(String[] args) throws Exception{
Scanner sc = new Scanner(System.in);
while(sc.hasNextLine()){
String s = sc.nextLine();
char[] cc = s.toCharArray();
int count = 0;
HashSet<Character> set = new HashSet<>();
for(int i = 0; i < cc.length; ++i){
if(cc[i] >= 0 && cc[i] <= 127){
if(!set.contains(cc[i])){
set.add(cc[i]);
count++;
}
}
}
System.out.println(count);
}
}
} 


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