package main import ( "bufio" "os" "strconv" "fmt" ) type Scanner struct { r *bufio.Reader buf []byte p int } func NewScanner() *Scanner { rdr := bufio.NewReaderSize(os.Stdin, 1000) return &Scanner{r:rdr} } func (s *Scanner) Next() string { s.pre() start := s.p for ; s.p < len(s.buf); s.p++ { if s.buf[s.p] == ' ' { break } } result := string(s.buf[start:s.p]) s.p++ return result } func (s *Scanner) NextLine() string { s.pre() start := s.p s.p = len(s.buf) return string(s.buf[start:]) } func (s *Scanner) NextInt() int { v, _ := strconv.Atoi(s.Next()) return v } func (s *Scanner) NextInt64() int64 { v, _ := strconv.ParseInt(s.Next(), 10, 64) return v } func (s *Scanner) NextIntArray() []int { s.pre() start := s.p result := []int{} for ; s.p < len(s.buf) + 1; s.p++ { if s.p == len(s.buf) || s.buf[s.p] == ' ' { v, _ := strconv.ParseInt(string(s.buf[start:s.p]), 10, 0) result = append(result, int(v)) start = s.p + 1 } } return result } func (s *Scanner) NextInt64Array() []int64 { s.pre() start := s.p result := []int64{} for ; s.p < len(s.buf) + 1; s.p++ { if s.p == len(s.buf) || s.buf[s.p] == ' ' { v, _ := strconv.ParseInt(string(s.buf[start:s.p]), 10, 64) result = append(result, v) start = s.p + 1 } } return result } func (s *Scanner) NextMap() map[int]bool { s.pre() start := s.p mp := map[int]bool{} for ; s.p < len(s.buf); s.p++ { if s.buf[s.p] == ' ' { v, _ := strconv.Atoi(string(s.buf[start:s.p])) mp[v] = true start = s.p + 1 } } v, _ := strconv.Atoi(string(s.buf[start:s.p])) mp[v] = true return mp } func (s *Scanner) pre() { if s.p >= len(s.buf) { s.readLine() s.p = 0 } } func (s *Scanner) readLine() { s.buf = make([]byte, 0) for { l, p, e := s.r.ReadLine() if e != nil { panic(e) } s.buf = append(s.buf, l...) if !p { break } } } func main() { sc := NewScanner() H := sc.NextInt() W := sc.NextInt() N := sc.NextInt() K := sc.NextInt() if (H * W - 1) % N + 1 == K { fmt.Println("YES") } else { fmt.Println("NO") } }