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