#include <stdio.h>

int main() {
    char arr[501] = " ";
    scanf("%s",arr);
    int arr1[128] = {0};
    int d = 0;
    for(int i = 0;i<strlen(arr);i++)
    {
        arr1[arr[i]]++;
    }
    int count = 0;
    for(int i = 0;i<128;i++)
    {
        if(arr1[i])
        {
            count++;
        }
    }
    printf("%d",count);
    return 0;
}