#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main(){
    char s[100];
    int i,length,count=0;
    fgets(s,sizeof(s),stdin);
    length=strlen(s);
    if(s[length-1]=='\n'){
        s[length-1]='\0';
        length--;
    }
    for( i=0;i<length;i++){
        if(!isalpha(s[i]&&s[i]){
            printf("Invalid input");
            return 0;
        }
    }
    while(length>0;&&s[length-1]){
        length--;
    }
    for( i=length-1;i>=0;&&s[i];i--){
        count++;
    }
    printf("%d",count);
    return 0;
}