#include <stdio.h>
#include <string.h>
#include <ctype.h>

int main(){
    char s[100];
    int valid=1;
    size_t len=strlen(s);
    if (s[len-1=='\n']){
        s[len-1]='\0';
        len--;
    }
    for (inti=0;i<len;i++){
        if(!(isalpha(s[i]) ||isspace(s[i])))
        {
            valid=0;
            break;
        }
    }
    if(!valid){
        printf("Invalid input\n");
        return 0;
    }
    int i=len-1;
    while(i>=0 && isalpha(s[i])){
        count++;
    }
    printf("%d\n",count);
    return 0;
}