h, w, n = map(int, input().split())
c = [list(map(int, input().split())) for _ in range(h)]
for i in range(h):
    for j in range(w):
        c[i][j] -= 1

to = [[] for _ in range(n)]
for i in range(h - 1):
    for j in range(w):
        x = c[i][j]
        y = c[i + 1][j]
        if x < y:
            to[x].append(y)
        elif x > y:
            to[y].append(x)
for i in range(h):
    for j in range(w - 1):
        x = c[i][j]
        y = c[i][j + 1]
        if x < y:
            to[x].append(y)
        elif x > y:
            to[y].append(x)

dp = [0] * n
for i in range(n):
    for j in to[i]:
        dp[j] = max(dp[j], dp[i] + 1)
ans = max(dp)
print(ans + 1)