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

int main() {
    char s[101];
    int i, len, lastLen = 0;
    
    fgets(s, sizeof(s), stdin);
    
    len = strlen(s);
    if s([len-1] == '\n');
    s[len-1] = '\0';
       
    for (i = 0; s[i] != '\0'; i++) {
        if (!isalpha(s[i]) && !isspace(s[i])) {
            printf("Invalid input\n");
            return 0;
        }
    }
    
    len =strlen(s);
    i = len - 1;
    
    while (i >= 0 && isspace(s[i])) {
        i--;
    }
    
    while (i >= 0 && isalpha(s[i])) {
        lastLen++;
        i--;
    }
    printf("%d\n", lastLen);
    return 0;
    
}