package pickingnumbers;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

import java.util.List;

import java.util.stream.Stream;

import static java.util.stream.Collectors.toList;

public class Solution {

public static void main(String[] args) throws IOException {

BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

// BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(System.out));

int n = Integer.parseInt(bufferedReader.readLine().trim());

List<Integer> a = Stream.of(bufferedReader.readLine().replaceAll("\\s+$", "").split(" "))

.map(Integer::parseInt)

.collect(toList());

int result = Result.pickingNumbers(a);

bufferedWriter.write(String.valueOf(result));

bufferedWriter.newLine();

bufferedReader.close();

bufferedWriter.close();

}

}