#include <stdio.h>
 
int main(int argc, char* argv[])
{
  int length, i, c;
  long max = 0;
  scanf("%d", &length);
 
  int arr[length];
  for (i = 0; i < length; i++)
    scanf("%d", &arr[i]);
 
  for (i = 0; i < length; i++)        // Условие для цикла можно было бы еще ограничить, но не катастрофа.
    for (c = i + 7; c < length; c++)
      if (((long) arr[i]*arr[c] > max))
        max = (long) arr[i]*arr[c];
 
  printf("%ld\n", max);
 
  return 0;
}

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MTIKMTIKMTEKMTEKNDUKMjMKMzQKNDUKMTAKNwoyMwozMAoyMw==

12
12
11
11
45
23
34
45
10
7
23
30
23