#ifdef LOCAL111 #else #define NDEBUG #endif #include const int INF = 1e8; using namespace std; #define endl '\n' #define ALL(a) (a).begin(),(a).end() #define SZ(a) int((a).size()) #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--) #define REP(i,n) FOR(i,0,n) #define RREP(i,n) for (int i=(n)-1;i>=0;i--) #define RBP(i,a) for(auto& i : a) #ifdef LOCAL111 #define DEBUG(x) cout<<#x<<": "<<(x)< void pite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;} template bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;} template bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;} typedef pair P; typedef long long int LL; typedef unsigned long long ULL; typedef pair LP; void ios_init(){ //cout.setf(ios::fixed); //cout.precision(12); #ifdef LOCAL111 return; #endif ios::sync_with_stdio(false); cin.tie(0); } int main() { ios_init(); LL n, m, x, y; cin >> n >> m >> x >> y; x--; y--; int cx = x%m; int ux = x/m; int cy = y%m; int uy = y/m; if(ux == 1){ cx = m-1-cx; } if(uy == 1){ cy = m-1-cy; } if(cx == cy) cout << "YES" << endl; else cout << "NO" << endl; return 0; }