#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main() {
    char str1[20], str2[20];
    int freq[26] = {0};
    scanf("%s", str1);
    scanf("%s", str2);
    int len1 = strlen(str1);
    int len2 = strlen(str2);
    if (len1 < 1 || len1 > 10 || len2 < 1 || len2 > 10) {
        printf("Invalid input");
        return 0;
    }
    for (int i = 0; i < len1; i++) {
        if (!isalpha(str1[i])) {
            printf("Invalid input");
            return 0;
        }
    }
    for (int i = 0; i < len2; i++) {
        if (!isalpha(str2[i])) {
            printf("Invalid input");
            return 0;
        }
    }
    if (len1 != len2) {
        printf("NO");
        return 0;
    }
    for (int i = 0; i < len1; i++) {
        freq[tolower(str1[i]) - 'a']++;
        freq[tolower(str2[i]) - 'a']--;
    }
    for (int i = 0; i < 26; i++)  {
        if (freq[i] != 0) {
            printf("NO");
            return 0;
        }