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

int main(){
    char s[25];
    fgets(s,sizeof(s),stdin);
    s[strcspn(s,"\n")]='\0';
    int length =strlen(s);
    if (length<1|| length >20){
        printf("Invalid input\n");
        return 0;
    }
    for(int i=0;i<length;i++){
        if(!isalpha(s[i]) && s[i] != '') {
            printf("Invalid input\n");
            return 0;
        }
    }
    int lastwordlength=0;
    int i=length-1;
    
    while(i>=0 && s[i]== ''){
        i--;
    }
    while(i>=0 && s[i] != ''){
        lastwordlength++;
        i++;
    }
    printf("%d\n",lastwordlength);
    return 0;
}