def dfs(v, visited):
    global edges, matched
    for u in edges[v]:
        if u in visited:
            continue
        visited.add(u)
        if matched[u] == -1 or dfs(matched[u], visited):
            matched[u] = v
            return True
    return False
    
def mpc(xn, yn):
    global matched, edges
    matched = [-1] * yn

    left = xn
    right = 0

    ledges = []
    redges = matched

    for v in range(xn):
        if not dfs(v, set()):
            left -= 1
            ledges.append(v)
    for v in ledges:
        for u in edges[v]:
            right += 1
            if redges[u] >= 0:
                left -= 1

    return left + right


if __name__ == '__main__':
    H, W = map(int, input().split())

    S = dict()

    for i in range(H):
        for j, a in enumerate(list(map(int, input().split()))):
            if a > 0:
                if a not in S:
                    S[a] = [set([i]), set([j])]
                S[a].append((i, j))
                S[a][0].add(i)
                S[a][1].add(j)
                    
    
    cnt = 0
    for pairs in S.values():
        hl = list(pairs[0])
        wl = list(pairs[1]) 
        h = len(hl)
        w = len(wl)
        edges = [set() for _ in range(h)]
        for i, j in pairs[2:]:
            edges[hl.index(i)].add(wl.index(j))
        n = mpc(h, w)
        cnt += n
    
    print(cnt)