Problem:
Score : 300 points

Problem Statement

There are N integers, A_1, A_2, ..., A_N, written on the blackboard.

You will choose one of them and replace it with an integer of your choice between 1 and 10^9 (inclusive), possibly the same as the integer originally written.

Find the maximum possible greatest common divisor of the N integers on the blackboard after your move.

Constraints

All values in input are integers.

2 \leq N \leq 10^5

1 \leq A_i \leq 10^9

Output

Input is given from Standard Input in the following format:

N
A_1 A_2 ... A_N

Output

Print the maximum possible greatest common divisor of the N integers on the blackboard after your move.

Sample Input 1

3
7 6 8

Sample Output 1

2

If we replace 7 with 4, the greatest common divisor of the three integers on the blackboard will be 2, which is the maximum possible value.

Sample Input 2

3
12 15 18

Sample Output 2

6

Sample Input 3

2
1000000000 1000000000

Sample Output 3

1000000000

We can replace an integer with itself.

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

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

int N;
long *arr;
long i;

long asc(const void *a, const void *b)
{
    return *(long*)a - *(long*)b;
}

long calc(long *a, long *b){
    long r = *a % *b;
    while(r!=0){
        *a = *b;
        *b = r;
        r = *a % *b;
    }
    return *b;
}

int main(int argc, char *argv[])
{
    long y;
    scanf("%ld",&N);
    arr = (long*)malloc(N*sizeof(long));
    for (i = 0; i < N; i++) scanf("%ld",&arr[i]);
    qsort(arr, N ,sizeof(long),asc);
    y = calc(&arr[N],&arr[N-1]);
    printf("%ld", y);
    return 0;
}