N,M=map(int,input().split())
MAP=[input() for i in range(N)]

def findmap(x0,y0,di):
    USE=[[0]*M for i in range(N)]

    Q=[(x0,y0,di)]
    while Q:
        x,y,di=Q.pop()
        if USE[x][y]==1:
            if x==x0 and y==y0:
                break
            else:
                return False
            
        USE[x][y]=1

        if di=="R":
            if 0<=x<N and 0<=y+1<M and MAP[x][y+1]==".":
                Q.append((x,y+1,"R"))
            elif 0<=x-1<N and 0<=y<M and MAP[x-1][y]==".":
                Q.append((x-1,y,"U"))
            else:
                return False

        elif di=="L":
            if 0<=x<N and 0<=y-1<M and MAP[x][y-1]==".":
                Q.append((x,y-1,"L"))
            elif 0<=x+1<N and 0<=y<M and MAP[x+1][y]==".":
                Q.append((x+1,y,"D"))
            else:
                return False

        elif di=="U":
            if 0<=x-1<N and 0<=y<M and MAP[x-1][y]==".":
                Q.append((x-1,y,"U"))
            elif 0<=x<N and 0<=y-1<M and MAP[x][y-1]==".":
                Q.append((x,y-1,"L"))
            else:
                return False

        elif di=="D":
            if 0<=x+1<N and 0<=y<M and MAP[x+1][y]==".":
                Q.append((x+1,y,"D"))
            elif 0<=x<N and 0<=y+1<M and MAP[x][y+1]==".":
                Q.append((x,y+1,"R"))
            else:
                return False

    for i in range(N):
        for j in range(M):
            if MAP[i][j]=="." and USE[i][j]==0:
                return False
    return True

for x in range(N):
    for y in range(M):
        if 0<=x+1<N and 0<=y<M and MAP[x+1][y]==".":
            if findmap(x,y,"D")==True:
                print("YES")
                exit()
        if 0<=x-1<N and 0<=y<M and MAP[x-1][y]==".":
            if findmap(x,y,"U")==True:
                print("YES")
                exit()
        if 0<=x<N and 0<=y+1<M and MAP[x][y+1]==".":
            if findmap(x,y,"R")==True:
                print("YES")
                exit()
        if 0<=x<N and 0<=y-1<M and MAP[x][y-1]==".":
            if findmap(x,y,"L")==True:
                print("YES")
                exit()
else:
    print("NO")