#include<stdio.h>

int main(){
    char c;
    int hash[300] = {0};
    int ans=0;
    while((c = getchar()) != '\n'){
        if (c != ' '){
            if (hash[(int)c] == 0){
                hash[(int)c] = 1;
                ans++;
            }
        }
    }
    
    printf("%d",ans);
    
    return 0;
}