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

int main(){
    char s[25];
    fgets(s,sizeof(s),stdin);
    
    int len = strlen(s)
    if(s[len-1]=='\n'){
        s[len-1]='\0';
        len--;
    }
    
    for (int i=0; i<len; i++){
        if(!(isaplha(s[i])|| s[i]==' ')){
            printf("Invalid input");
            return 0;
        }
    }
    
    int i = len-1;
    
    while (i>=0&& s[i]==' '){
        i--;
    }
    int wordLength=0;
    while(i>=0 && s[i]!=''){
        wordLength++;
        i--;
    }
    printf("%d", wordLength);
    return 0;
}