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

class topological_sort():
    #1-indexed
    #0-indexedはバグる
    def __init__(self,n):
        self.n=n
        self.root=[[] for _ in range(self.n+1)]
        self.deg=[0]*(self.n+1)
    def add(self,a,b):
        #有向辺 a->b の追加
        self.root[a].append(b)
        self.deg[b]+=1
    def const(self):
        #トポロジカルソートした結果を返す
        #不可能なら [] を返す
        deg2=self.deg[:]
        search=[]
        res=[]
        for i in range(1,self.n+1):
            if deg2[i]==0:search.append(i)
        while search:
            now=search.pop()
            res.append(now)
            for next in self.root[now]:
                deg2[next]-=1
                if deg2[next]==0:
                    search.append(next)
        if len(res)==self.n:
            return res
        return []

delta=[(1,0),(-1,0),(0,1),(0,-1)]

for i in range(h):
    for j in range(w):
        for di,dj in delta:
            if i+di<0 or i+di>=h or j+dj<0 or j+dj>=w:continue

            if c[i][j]>c[i+di][j+dj]:
                root[c[i+di][j+dj]].append((c[i][j],1))

dp=[1]*(n+1)
for i in range(1,n):
    root[i].append((i+1,0))
for x in range(n,0,-1):
    for y,cost in root[x]:
        dp[x]=max(dp[x],dp[y]+cost)
print(max(dp))