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

int main() {
    char s[21];
    fgets(s, sizeof(s), stdin);
    s[strcspn(s, "\n")] = 0;
    
    for (char * p = s; * p; p++)
        if (!isalpha(*p) && * p != '') {
        printf("Invalid input\n");
        return 0;
    }
    
    char *last = strrchr(s, '');
    int len = last ? strlen(last + 1) : strlen(s);
    printf("%d\n", len);
    return 0;
}