Bitwise operations
Sometimes we need to perform operations on pairs of binary numbers. If we have two numbers
a and b, we might want to have all the bits set to 0s except the ones that are 1 in both a and b (this corresponds to an AND operation). We might otherwise want to have all ones in positions where either a or b have a 1 there (this corresponds to an OR operation).a | b | a & b (AND) | a | b (OR) | a ^ b (XOR)
exclusive OR |
binary and decimal representations | binary and decimal representations | 1 if both and are 1 and 0 otherwise | 1 if either or are 1 and 0 otherwise | 1 if bits are different and 0 otherwise |
110 (6) | 101 (5) | 100 (4) | 111 (7) | 011 (3) |
100111 (39) | 010100 (20) | 100 (4) | 110111 (55) | 110011 (51) |
Challenge
Given
n integers, you are asked to find 2 of those that after applying OR to them would result in the largest number.Input
The first line of the input contains a single integer
n (1 ≤ n ≤ 1000).The next line contains
n space-separated integers (1 ≤ ≤ ).Output
The output should contain the largest value you can obtain by applying an OR operation on 2 values from the given numbers.
Examples
Input | Output |
5
1 2 3 4 5 | 7 |
Explanation
We can obtain 7 by applying OR to:
- 2 (
010) and 5 (101) → 7 (111)
- 3 (
011) and 4 (100) → (111)
Constraints
Time limit: 2.4 seconds
Memory limit: 512 MB
Output limit: 1 MB