#==================================================
from itertools import product
H,W,N=map(int,input().split())
C=[]
for _ in range(H):
    C.append(list(map(int,input().split())))

T=[(1,0),(0,1)]
E=[[] for _ in range(N+1)]
for i,j in product(range(H),range(W)):
    for a,b in T:
        if 0<=i+a<H and 0<=j+b<W:
            alpha=min(C[i][j],C[i+a][j+b])
            beta =max(C[i][j],C[i+a][j+b])
            E[alpha].append(beta)

DP=[0]*(N+1)
for x in range(N,0,-1):
    m=0
    for y in E[x]:
        m=max(m,DP[y])
    DP[x]=m+1

print(max(DP))