def add_edge(u, v):
    global match
    G[u].append(v)
    G[v].append(u)
    
def dfs(v):
    global match, G, used
    used[v] = True
    for i in range(len(G[v])):
        u = G[v][i]
        w = match[u]
        if w < 0 or not used[w] and dfs(w):
            match[v] = u
            match[u] = v
            return True
    return False

def bipartite_matching():
    global match, V, used
    res = 0
    match = [-1] * V
    for v in range(V):
        if match[v] < 0:
            used = [False] * V
            if dfs(v):
                res += 1
    return res

def matches(h, w, edges):
    global G, V, match
    V = h + w
    G = [[] for _ in range(V)]
    for v in range(h):
        for u in edges[v]:
            add_edge(v, u+h)
        
    res = bipartite_matching()
    return match[h:h+w]
    
def mpc(xn, yn):
    global edges
    matched = matches(xn, yn, edges)

    left = xn
    right = 0

    redges = matched
    
    for v in range(xn):
        if v not in matched:
            left -= 1
            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] = [[], []]
                if i in S[a][0]:
                    ai = S[a][0].index(i)
                else:
                    ai = len(S[a][0])
                    S[a][0].append(i)
                if j in S[a][1]:
                    aj = S[a][1].index(j)
                else:
                    aj = len(S[a][1])
                    S[a][1].append(j)                    
                S[a].append((ai, aj))

    cnt = 0
    for a, pairs in S.items():
        h = len(pairs[0])
        w = len(pairs[1])
        edges = [set() for _ in range(h)]
        for i, j in pairs[2:]:
            edges[i].add(j)
        n = mpc(h, w)
        cnt += n
    
    print(cnt)