import sequtils,strutils
var M,N : int
(M, N) = stdin.readline.split.map(parseInt)
var
    hyou = newSeq[string](M + 2,)
    D = [[1,0],[0,-1],[-1,0],[0,1]]
    cnt : int
    ans : bool
    cntd : int
    flag : array[102,array[102,int]]
    
hyou[0] = repeat('#',M + 2)
hyou[M + 1] = repeat('#',M + 2)

for n in 1..M:
    hyou[n] = '#' & stdin.readline & '#'




proc tansaku(i,j : int):bool=
    var
        x = i
        y = j
        cntf = 0
        cntf2 = 0
        nx,ny : int
    for d2 in 0..3:
        var d = d2
        while cntf <= cntd:
            nx = x + D[d][0]
            ny = y + D[d][1]
            if nx == i and ny == j and cntf == cntd - 1:
                return true
            elif hyou[ny][nx] == '.' and flag[ny][nx] < cnt:
                flag[ny][nx] = cnt
                cntf += 1
                x = nx
                y = ny
                cntf2 = 0
            elif cntf2 == 0:
                cntf2 += 1
                d = (d + 1) mod 4
            else:
                break
    return false
            
        
for x in 1..N:
    for y in 1..M:
        if hyou[y][x] == '.':
            cntd += 1

block tansaku:
    if cntd > 4 * (M + N):
        break tansaku
    for x in 1..N:
        for y in 1..M:
            if hyou[y][x] == '.':
                cnt += 1
                if tansaku(x,y):
                    ans = true
                    break tansaku
if ans:
    echo "YES"
else:
    echo "NO"