Buggy python submission (verdict: Runtime Error):
H, W, N = map(int, input().split())
sr, sc = map(int, input().split())
S = input()
T = input()

left = 1
right = W
up = 1
down = H

for i in reversed(range(N)):
    if i != N - 1:
        if T[i] == "U":
            if down != H:
                down -= 1
        elif T[i] == "D":
            if up != 1:
                up += 1
        elif T[i] == "L":
            if right != W:
                right += 1
        else:
            if left != 1:
                left -= 1
    if S[i] == "U":
        up -= 1
    elif S[i] == "D":
        down += 1
    elif S[i] == "L":
        left += 1
    else:
        right -= 1
    if left == right or up == down:
        print("NO")
        exit()
if left <= sr <= right and up <= sc <= down:
    print("YES")
else:
    print("NO")


Fixed submission:
def main():
    from collections import deque
    H, W = map(int, input().split())
    grid = [["#"] * (W + 2)] + [list("#" + input() + "#")
                                for i in range(H)] + [["#"]*(W+2)]
    # print(grid)
    stack = deque()
    for h in range(1, H+1):
        for w in range(1, W+1):
            # 黒ならスタックにpush
            if grid[h][w] == "#":
                stack.append([h, w])

    for i in range(h + w + 3):
        tmp = deque()
        while stack:
            h, w = stack.pop()
            for dh, dw in ([0, 1], [0, -1], [1, 0], [-1, 0]):
                if grid[h + dh][w + dw] == ".":
                    grid[h + dh][w + dw] = "#"
                    tmp.append([h + dh, w + dw])
        stack = tmp
        if not stack:
            print(i)
            break


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
def main():
    from collections import deque
    H, W = map(int, input().split())
    grid = [["#"] * (W + 2)] + [list("#" + input() + "#")
                                for i in range(H)] + [["#"]*(W+2)]
    # print(grid)
    stack = deque()
    for h in range(1, H+1):
        for w in range(1, W+1):
            # 黒ならスタックにpush
            if grid[h][w] == "#":
                stack.append([h, w])

    for i in range(h + w + 3):
        tmp = deque()
        while stack:
            h, w = stack.pop()
            for dh, dw in ([0, 1], [0, -1], [1, 0], [-1, 0]):
                if grid[h + dh][w + dw] == ".":
                    grid[h + dh][w + dw] = "#"
                    tmp.append([h + dh, w + dw])
        stack = tmp
        if not stack:
            print(i)
            break


if __name__ == '__main__':
    main()


Fixed submission:
def main():
    from collections import deque
    H, W = map(int, input().split())
    grid = [["#"] * (W + 2)] + [list("#" + input() + "#")
                                for i in range(H)] + [["#"]*(W+2)]
    # print(grid)
    stack = deque()
    for h in range(1, H+1):
        for w in range(1, W+1):
            # 黒ならスタックにpush
            if grid[h][w] == "#":
                stack.append([h, w])

    for i in range(h + w + 3):
        tmp = deque()
        while stack:
            h, w = stack.pop()
            for dh, dw in ([0, 1], [0, -1], [1, 0], [-1, 0]):
                if grid[h + dh][w + dw] == ".":
                    grid[h + dh][w + dw] = "#"
                    tmp.append([h + dh, w + dw])
        stack = tmp
        if not stack:
            print(i)
            break


if __name__ == '__main__':
    main()