#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main(){
    char s[21];
    fgets(s, sizeof(s), stdin);
    s[strcspn(s, "\n")] = 0;
    
    for(char *p =s;*p;p++)
    if(!isalpha(*p)&&*p!=''){
        printf("Invalid input\n");
        return 0;
    }
    char*last=strrchr(s,'');
    int len = last? strlen(last+ 1):
    strlen(s);
printf("%d\n", len);
return 0;
}