22

import java.util.Arrays;
import java.util.Scanner;

public class Main{
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int[]child = strToArray(sc.nextLine().split(" "));
        int[]candy = strToArray(sc.nextLine().split(" "));
        int i=0,j=0,cnt=0;
        while(i<child.length && j<candy.length) {
            if(child[i]<=candy[j]) {
                ++i;
                ++cnt;
            }
            ++j;
        }
        System.out.println(cnt);

    }

    public static int max(int... a) {
        return Arrays.stream(a).max().getAsInt();
    }
    public static int[] strToArray(String[] a) {
        int[]p = Arrays.stream(a).mapToInt(Integer::valueOf).toArray();
        return p;
    }

}