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

int main(void){
    char s[256];
    if (!fgets(s, sizeof(s), stdin)) return 0;
    size_t n = strlen(s);
    if (n && s[n-1] == '\n') s[--n] = '\0';
    if (n < 1 || n > 20) {
        printf("Invalid input");
        return 0;
    }
    for (size_t i =0;i<n;++i){
        if (!(isalpha((unsigned char)s[i]) || s[i] == ' ')){
            printf("Invalid input");
            return 0;
        }
    }
    long i = (long)n - 1;
    while (i > 0 && s[i] == ' ')--i;
    if (i < 0){ printf("0");
    return 0;
    long j = i;
    while (j >= 0 && s[j]!= ' ')--j;
    printf("%ld", i - j);
    return 0;
        
    }