#include<stdio.h>
#include<string.h>
#include<ctype.h>
in main(){
    char s[21];
    fgets(s, size of(s),stdin);
    int len=strlen(s);
    if (len>0 && s[len-1]== '\n') s [len-1]='\0';
    for (int i = 0; s[i]; i++) {
        if (!isalpha(s[i]) && s[i]!= ''){
            printf("Invalid input\n");
            return 0;
        }
    }
    char*last_word=strrchr(s, '');
    if (last_word) last_word++;
    else last_word =s;
    printf("%lu\n",strlen(last_word));
    return 0;
}