#!/usr/bin/env python
# -*- coding:utf-8 -*-


def find_num(alist, T):
    mark = {}
    for v in alist:
        mark[v] = True

    result = []
    for v in alist:
        if not mark[v]:
            continue
        if v == T:
            result.append([v])
            mark[v] = False
            continue

        if mark.__contains__(T-v) and mark[T - v]:
            result.append([v, T - v])
            mark[v] = False
            mark[T - v] = False

    return result


if __name__ == '__main__':
    n = 0
    T = 0
    while True:
        print("input T:")
        T = int(input())
        print('input data length:')
        n = int(input())
        print('input digits: ')
        alist = []
        for i in range(0, n):
            digit = int(input())
            alist.append(digit)

        result = find_num(alist, T)
        print(result)