#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ul = unsigned long;
using ull = unsigned long long;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int n,m;
    cin >> n >> m;
    
    int c[2];
    for(int i=0;i<2;++i)
    {
        int x;
        cin >> x;
        c[i]=--x % (m * 2);
        if (c[i] >= m)
            c[i] = m * 2 - 1 - c[i];
    }
    
    cout << (c[0] == c[1] ? "YES\n":"NO\n");

	return 0;
}