package main import ( "bufio" "fmt" "os" "sort" "strconv" ) func out(x ...interface{}) { fmt.Println(x...) } var sc = bufio.NewScanner(os.Stdin) func getInt() int { sc.Scan() i, e := strconv.Atoi(sc.Text()) if e != nil { panic(e) } return i } func getInts(N int) []int { ret := make([]int, N) for i := 0; i < N; i++ { ret[i] = getInt() } return ret } func getString() string { sc.Scan() return sc.Text() } // min, max, asub, absなど基本関数 func max(a, b int) int { if a > b { return a } return b } func min(a, b int) int { if a < b { return a } return b } func asub(a, b int) int { if a > b { return a - b } return b - a } func abs(a int) int { if a >= 0 { return a } return -a } func lowerBound(a []int, x int) int { idx := sort.Search(len(a), func(i int) bool { return a[i] >= x }) return idx } func upperBound(a []int, x int) int { idx := sort.Search(len(a), func(i int) bool { return a[i] > x }) return idx } var H, W int var s []string var tot int func match(dx, dy int) bool { u := make([][]int, H) for i := 0; i < H; i++ { u[i] = make([]int, W) } r, b := 0, 0 // out("------") for y := 0; y < H; y++ { for x := 0; x < W; x++ { rx, ry := x, y bx, by := x+dx, y+dy if bx >= W || by >= H { continue } if u[ry][rx] == 0 && s[ry][rx] == '#' { b++ if s[by][bx] == '#' { // out("x", by, bx) u[by][bx] = 1 r++ } } } } // for y := 0; y < H; y++ { // // for x := 0; x < W; x++ { // out(u[y]) // // } // } // out(r, b, tot) if r == b && r+b == tot { return true } return false } func main() { sc.Split(bufio.ScanWords) sc.Buffer([]byte{}, 1000000) H, W = getInt(), getInt() s = make([]string, H) for i := 0; i < H; i++ { s[i] = getString() } for y := 0; y < H; y++ { for x := 0; x < W; x++ { if s[y][x] == '#' { tot++ } } } for y := 0; y < H; y++ { for x := 0; x < W; x++ { if x == 0 && y == 0 { continue } ret := match(x, y) // out(x, y, ret) if ret == true { out("YES") return } } } out("NO") }