4번 문제만 시간초과나는데 괜찮나여??

sys.setrecursionlimit(10**6)

def DFS(x, y, w):
    ch[x][y] = 1
    for i in range(4):
        a = x + dx[i]
        b = y + dy[i]
        if 0 <= a < n and 0 <= b < n and tmp[a][b] > w and ch[a][b] == 0:
            DFS(a, b, w)


dx = [-1, 0, 1, 0]
dy = [0, 1, 0, -1]
n = int(input())
tmp = [list(map(int, input().split())) for _ in range(n)]
count = 0
res = 0

for i in range(100):
    count = 0
    ch = [[0] * n for _ in range(n)]
    for j in range(n):
        for k in range(n):
            if ch[j][k] == 0 and tmp[j][k] > i:
                count += 1
                DFS(j, k, i)

    if res < count:
        res = count

    if count == 0:
        break
print(res)

5번은 통과하는데 4번만 시간초과합니다

컴퓨터 문제일까요??