import java.awt.geom.Point2D; import java.io.*; import java.math.BigInteger; import java.util.ArrayDeque; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.Comparator; import java.util.Deque; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.NoSuchElementException; import java.util.PriorityQueue; import java.util.Scanner; import java.util.Stack; import java.util.TreeMap; public class Main { static PrintWriter out = new PrintWriter(System.out); static FastScanner sc = new FastScanner(); static Scanner stdIn = new Scanner(System.in); public static void main (String[]agrs){ long h = sc.nextLong(); long w = sc.nextLong(); long n = sc.nextLong(); long k = sc.nextLong(); long sum = h * w; sum %= n; if(sum == 0) { sum = n; } if(sum == k) { System.out.println("YES"); } else { System.out.println("NO"); } out.flush(); } } //------------------------------// //-----------// class FastScanner { private final InputStream in = System.in; private final byte[] buffer = new byte[1024]; private int ptr = 0; private int buflen = 0; private boolean hasNextByte() { if (ptr < buflen) { return true; }else{ ptr = 0; try { buflen = in.read(buffer); } catch (IOException e) { e.printStackTrace(); } if (buflen <= 0) { return false; } } return true; } private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;} private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;} private void skipUnprintable() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;} public boolean hasNext() { skipUnprintable(); return hasNextByte();} public String next() { if (!hasNext()) throw new NoSuchElementException(); StringBuilder sb = new StringBuilder(); int b = readByte(); while(isPrintableChar(b)) { sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } public long nextLong() { if (!hasNext()) throw new NoSuchElementException(); long n = 0; boolean minus = false; int b = readByte(); if (b == '-') { minus = true; b = readByte(); } if (b < '0' || '9' < b) { throw new NumberFormatException(); } while(true){ if ('0' <= b && b <= '9') { n *= 10; n += b - '0'; }else if(b == -1 || !isPrintableChar(b)){ return minus ? -n : n; }else{ throw new NumberFormatException(); } b = readByte(); } } public int nextInt() { if (!hasNext()) throw new NoSuchElementException(); int n = 0; boolean minus = false; int b = readByte(); if (b == '-') { minus = true; b = readByte(); } if (b < '0' || '9' < b) { throw new NumberFormatException(); } while(true){ if ('0' <= b && b <= '9') { n *= 10; n += b - '0'; }else if(b == -1 || !isPrintableChar(b)){ return minus ? -n : n; }else{ throw new NumberFormatException(); } b = readByte(); } } public double nextDouble() { return Double.parseDouble(next()); } }