# Pair Sums

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#
#   You have been given an integer array A and a number K. Now, you need to find out whether any two different
#   elements of the array A sum to the number K. Two elements are considered to be different if they lie at
#   different positions in the array. If there exists such a pair of numbers, print "YES" (without quotes),
#   else print "NO" without quotes.
#
#   Input Format:
#   The first line consists of two integers N , denoting the size of array A and K. The next line consists of N
#   space separated integers denoting the elements of the array A
#
#   Output Format:
#   Print the required answer on a single line.
#
#   Constraints:
#   1 <= N <= 106
#   1 <= K <= 2∗106
#   1 <= A[i] <= 106
#
#   SAMPLE INPUT
#   5 9
#   1 2 3 4 5
#
#   SAMPLE OUTPUT
#   YES
#
#   Explanation
#   Here, A[4]+A[5] = 4+5 = 9. So, the answer is YES.
#
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