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

int* solution(int* nums, int numsSize, int* returnSize) {
    int* result = malloc(2 * sizeof(int));
    int resultIdx = 0;
    
    for (int i = 0; i < numsSize; i++) {
        int count = 0;
        for (int j = 0; j < numsSize; j++) {
            if (nums[j] == nums[i]) {
                count++;
            }
        }
        
        if (count == 1) {
            int found = 0;
            for (int k = 0; k < resultIdx; k++) {
                if (result[k] == nums[i]) {
                    found = 1;
                    break;
                }
            }
            if (!found) {
                result[resultIdx++] = nums[i];
                if (resultIdx == 2) {
                    break;
                }
            }
        }
    }
    
    *returnSize = resultIdx;
    return result;
}

int main() {
    char line[1000];
    fgets(line, sizeof(line), stdin);
    
    // Simple parsing for [1,2,3,4] format
    int nums[100];
    int numsSize = 0;
    char* token = strtok(line, "[,]");
    while (token != NULL) {
        if (strlen(token) > 0 && token[0] != '\n' && token[0] != '\r') {
            nums[numsSize++] = atoi(token);
        }
        token = strtok(NULL, "[,]");
    }
    
    int returnSize;
    int* result = solution(nums, numsSize, &returnSize);
    
    printf("[");
    for (int i = 0; i < returnSize; i++) {
        printf("%d", result[i]);
        if (i < returnSize - 1) printf(",");
    }
    printf("]\n");
    
    free(result);
    return 0;
}