events.cpp

#include <iostream>
#include <fstream>
#include <algorithm>

using namespace std;

int main() {
//  uncomment the following lines if you want to read/write from files
//  ifstream cin("input.txt");
//  ofstream cout("output.txt");
	
	int N1, N2;
    cin >> N1 >> N2;
    
    int P[N1], V[N2];
    for(int i=0; i<N1; i++)
        cin >> P[i];
    for(int i=0; i<N2; i++)
        cin >> V[i];

    // insert your code here
    int index=0, ans=0;
    
    sort(P, P+N1);
    sort(V, V+N2);
    reverse(P, P+N1);
    reverse(V, V+N2);
    
    for (int i=0; i<N2; i++) {
    	int vo = V[i];
    	if (index != N1) {
    		for (int j=index; j<N1; j++) {
    			if (vo >= P[j]) {
    				index = j+1;
    				ans ++;
    				break;
				}
			}
		} else {
            break;
        }
		
	}
    
    cout << ans << endl; // print the result
    return 0;
}