n, m = map(int, input().split())

mat = [list(map(int, input().split())) for _ in range(n)]

dist = [[-1] * m for _ in range(n)]

def dfs(i,j):
    if dist[i][j] > -1: return dist[i][j]
    dist[i][j] = 1
    cv = mat[i][j]
    for dx, dy in zip((-1, 0, 1, 0), (0, -1, 0, 1)):
        nx, ny = i + dx, j + dy
        if 0 <= nx < n and 0 <= ny < m and mat[nx][ny] < cv:
            dist[i][j] = max(dist[i][j], dfs(nx, ny) + 1)
    return dist[i][j]

print(max(dfs(i, j) for i in range(n) for j in range(m)))