package main

import (
    "bufio"
    "fmt"
    "os"
    "strconv"
)

func output(result string) {
    fmt.Println(result)
    f, _ := os.Create("output.txt")
    defer f.Close()
    f.WriteString(result)
}

func main() {
    file, _ := os.Open("input.txt")
    defer file.Close()

    scanner := bufio.NewScanner(file)
    scanner.Split(bufio.ScanWords)

    scanner.Scan()
    target, _ := strconv.Atoi(scanner.Text())

    m := make(map[int]struct{})
    for scanner.Scan() {
        num, _ := strconv.Atoi(scanner.Text())
        if num > target {
            continue
        }
        if _, found := m[target-num]; found {
            output("1")
            return
        }
        m[num] = struct{}{}
    }

    output("0")
}