#include <stdio.h>

int main() {
    char s[11];
    scanf("%s", s);
    for (int i = 0; i < 10, s[i] != '\0'; i++) {
        for (int j = i+1; j < 10, s[j] != '\0'; j++) {
            if (s[i] == s[j]) {
                printf("NO\n");
                return 0;
            }
        }
    }
    printf("YES\n");
    return 0;
}