#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main() {
    char s[101];
    int length = 0,i
    int valid = 1;
    fgets(s, sizeof(s),stdin);
    int len = strlen(s);
    if (s[len - 1] == '\n')
    s[len - 1] = '\0';
    for (i = 0; s[i] != '\0'; i++) {
        if (!isalpha(s[i]) && s[i] != ' ')
        {
            valid = 0;
            break;
        }
    }
    if (!valid) {
        printf("Invalid input");
        return 0;
    }
    i = strlen(s) - 1;
    while (i >= 0 && s[i] == ' ')
    i--;
    while (i >= 0 && s[i] != ' ') {
        length++;
        i--;
    }
    printf("%d", length);
    return 0;
}