package stonehee.baekjoon;

import java.io.BufferedReader;

import java.io.IOException;

import java.util.Arrays;

public class SumForThreeNum {

public static void main(String[] args) throws IOException {

BufferedReader br = new BufferedReader(new java.io.InputStreamReader(System.in));

int len = Integer.parseInt(br.readLine());

int[] nums = new int[len];

for(int i = 0; i < len; i++) {

nums[i] = Integer.parseInt(br.readLine());

}

System.out.println(findMaxSum(nums));

}

private static int findMaxSum(int[] nums) {

int[] possibleNumbers = getPossibleNumbers(nums);

for(int i = nums.length -1; i > 0; i--) {

for (int j = 0; j <= i; j++) {

int targetNum = nums[i] - nums[j];

if(arrContainsTarget(targetNum,possibleNumbers)) {

return nums[i];

}

}

}

return 0;

}

private static int[] getPossibleNumbers(int[] nums) {

Arrays.sort(nums);

int[] possibleNumbers = new int[nums.length * nums.length];

int idx = 0;

for (int i : nums) {

for (int j : nums) {

possibleNumbers[idx++] = i + j;

}

}

Arrays.sort(possibleNumbers);

return possibleNumbers;

}

private static boolean arrContainsTarget(int target, int[] arr) {

int start = 0;

int end = arr.length - 1;

int mid = 0;

while(start <= end) {

mid = (start + end) / 2;

if(arr[mid] == target) return true;

if(arr[mid] < target) start = mid + 1;

else end = mid - 1;

}

return false;

}

}