import sys
input = sys.stdin.readline

H, W, N = map(int, input().split())
G = [[] for i in range(N)]
for i in range(H):
    C = list(map(int, input().split()))
    for j in range(W):
        G[C[j] - 1].append((i, j))

temp = [[0] * W for i in range(H)]
dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
ans = 1
que = []
for i in range(N):
    D = []
    val = 0
    for x, y in G[i]:
        for k in range(4):
            nx = x + dx[k]
            ny = y + dy[k]
            if nx < 0 or nx > H - 1 or ny < 0 or ny > W - 1:
                continue
            val |= temp[nx][ny]
        D.append((x, y))
    ans += val
    if val:
        for x, y in que:
            temp[x][y] = 0
        que = []
    for x, y in D:
        temp[x][y] = 1

    que.extend(D)

print(ans)