import java.util.*;
import java.lang.*;
import java.io.*;

class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
		int[] folder = new int[10];
    	long N = in.nextLong();
    	while(N != 0) {
        	folder[(int)N % 10]++;
        	N /= 10;
    	}
    	int sum = 0;
    	for (int i = 0; i < 10; i++)
        	if(folder[i]!=0) sum++;
        System.out.print(sum);	
	}
}