#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(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;
        }
    }
    char*token=strok(s," ");
    cahr*lastword=NULL;
    while(token!=NULL){
        lastword=token;
        token=strtok(NULL," ");
    }
    if (lastword !=NULL){
        printf("d",(int)strlen(lastword));
    }
    else{
        printf("Invalid input")
    }
    return 0;
    
}