// editor5

#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(){
        chars[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;
}