#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using ull = unsigned long long; using ll = long long; using lli = long long int; using ld = long double; using pa = pair; #define SORT(v, n) sort(v, v+n); #define ALL(v) v.begin(),v.end() #define VSORT(v) sort(ALL(v)) #define GRESORT(v) sort(ALL(v),greater()) #define REVERSE(v) reverse(ALL(v)) #define overlap(v) v.erase(unique(ALL(v)),v.end()) #define debug(x) cout << #x << ": " << x << endl #define FOR(i,a,b) for(int i = (a); i < (b); i++) #define rep(i,n) FOR(i,0,n) #define RFOR(i,a,b) for(int i = (b-1); i >= a; i--) #define rrep(i,n) RFOR(i,0,n) #define INF 999999999 #define mins(a,b) a = min(a,b) #define maxs(a,b) a = max(a,b) //4近傍 int dy[]={0, 0, 1, -1}; int dx[]={1, -1, 0, 0}; //8近傍 //int dy[]={0,0,1,-1,1,1,-1,-1}; //int dx[]={1,-1,0,0,1,-1,1,-1}; ll mod = 1000000007; void solve(){ ll n,m,x,y; cin >> n >> m >> x >> y; x--; y--; if(x / m % 2 == 0){ x = x % m + 1; }else{ x = m - x % m; } if(y / m % 2 == 0){ y = y % m + 1; }else{ y = m - y % m; } cout << (x == y ? "YES" : "NO") << endl; } int main(){ std::ios::sync_with_stdio(false); std::cin.tie(0); solve(); return 0; }