import java.util.ArrayList;
import java.util.Scanner;
 
class Main {
/*LEAFEAT*/
 
public static void main(String[] args) {
    Scanner reader = new Scanner(System.in);
    String firstLine = reader.nextLine();
    //N is the number of leaves
    int N = Integer.parseInt(firstLine.split(" ")[0]);
    ArrayList<Integer> leafNumbers = new ArrayList<Integer>();
    for(int i=1;i<=N;i++) {
        leafNumbers.add(i);
    }
    //K is the number of caterpillars
    byte K = Byte.parseByte(firstLine.split(" ")[1]);
 
    for (byte i=1;i<=K;i++) {
        int caterpillarLength = Integer.parseInt(reader.nextLine());
        for (int j=1;i<=N;j=j+caterpillarLength) {
            if(j <= N) {
                leafNumbers.remove((Integer) j);
            } else {
                break;
            }
        }
    }
    reader.close();
    //System.out.println(leafNumbers.toString());
 
    System.out.println(leafNumbers.size());
}
}

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2
2
2