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

#define MAX_VAL 10001
int freq[MAX_VAL] = {0};

int repeatedNTimes(int* nums, int numsSize) {
    int n = numsSize / 2;
    
    // Reset frequency array
    for (int i = 0; i < MAX_VAL; i++) freq[i] = 0;
    
    // First pass: count frequencies
    for (int i = 0; i < numsSize; i++) {
        freq[nums[i]]++;
    }
    
    // Second pass: find element with frequency n
    for (int i = 0; i < numsSize; i++) {
        if (freq[nums[i]] == n) {
            return nums[i];
        }
    }
    
    return -1; // Should never reach here
}

int main() {
    int nums[1000];
    int size = 0;
    char c;
    int num = 0;
    int sign = 1;
    int reading = 0;
    
    while ((c = getchar()) != '\n' && c != EOF) {
        if (c >= '0' && c <= '9') {
            num = num * 10 + (c - '0');
            reading = 1;
        } else if (c == '-') {
            sign = -1;
            reading = 1;
        } else if (reading) {
            nums[size++] = num * sign;
            num = 0;
            sign = 1;
            reading = 0;
        }
    }
    if (reading) nums[size++] = num * sign;
    
    printf("%d\n", repeatedNTimes(nums, size));
    return 0;
}