from collections import defaultdict
h,w = map(int,input().split())
A = [list(map(int,input().split())) for i in range(h)]

xy = [[] for i in range(5*10**5+5)]
for i in range(h):
    for j in range(w):
        xy[A[i][j]].append((i,j))

ans = 0
for i in range(5*10**5,0,-1):
    if xy[i] == []:
        continue
    dich = defaultdict(int)
    dicw = defaultdict(int)
    for x,y in xy[i]:
        dich[x] += 1
        dicw[y] += 1
    dels = set()
    while True:
        mh = 0
        ih = 0
        mw = 0
        iw = 0
        for k,v in dich.items():
            if v > mh:
                mh = v
                ih = k
        for k,v in dicw.items():
            if v > mw:
                mw = v
                iw = k
        if mh == mw == 0:
            break
        ans += 1
        if mh >= mw:
            dich[ih] = 0
            for x,y in xy[i]:
                if (x,y) in dels:
                    continue
                if x == ih:
                    dicw[y] -= 1
                    dels.add((x,y))
        else:
            dicw[iw] = 0
            for x,y in xy[i]:
                if (x,y) in dels:
                    continue
                if y == iw:
                    dich[x] -= 1
                    dels.add((x,y))

print(ans)