h, w, n = map(int, input().split())
a = [list(map(int, input().split())) for _ in range(h)]
inv = [0] * n
g = [[] for _ in range(n)]
for i in range(h):
    for j in range(w):
        if i < h - 1:
            if a[i][j] < a[i + 1][j]:
                g[a[i][j] - 1].append(a[i + 1][j] - 1)
                inv[a[i + 1][j] - 1] += 1
            elif a[i][j] > a[i + 1][j]:
                g[a[i + 1][j] - 1].append(a[i][j] - 1)
                inv[a[i][j] - 1] += 1
        if j < w - 1:
            if a[i][j] < a[i][j + 1]:
                g[a[i][j] - 1].append(a[i][j + 1] - 1)
                inv[a[i][j + 1] - 1] += 1
            elif a[i][j] > a[i][j + 1]:
                g[a[i][j + 1] - 1].append(a[i][j] - 1)
                inv[a[i][j] - 1] += 1
s = []
d = [0] * n
for i in range(n):
    if inv[i] == 0:
        s.append(i)
while s:
    p = s.pop()
    for node in set(g[p]):
        if d[node] < d[p] + 1:
            d[node] = d[p] + 1
        inv[node] -= 1
        if inv[node] == 0:
            s.append(node)
print(max(d) + 1)