#include <stdio.h>
#include <string.h>
#include <ctype.h>
int length_of_last_word(char *s){
    int len = strlen(s);
    for(int i = 0;i<len;i++){
        if(!isalpha (s[i])&& s[i] != ' '){
            return -1;
        }
    }
int count = 0;
int i = len -1;
while(i >= 0 && s[i] == ' '){
    i--;
}
while(i >= 0  && s[i] != ' '){
    count++;
    i--;
}
return count;
}
int main(){
    char s[21];
    fgets(s,sizeof(s),stdin);
    s[strcspn(s, "\n")]=0;
    int result = length_of_last_word(s);
    if(result == -1){
        printf("Invalid input\n");
    } else {
        printf("%d\n" , result);
    }
    return 0;
}
}