import sys
input = sys.stdin.readline

H,W=list(map(int,input().split()))
A=[list(map(int,input().split())) for i in range(H)]

CH=[0]*H
CW=[0]*W

for i in range(H):
    for j in range(W):
        if A[i][j]==1:
            CH[i]+=1
            CW[j]+=1

CH.sort(reverse=True)
CW.sort(reverse=True)

i=0
j=0

while i<len(CH) and j<len(CW):
    if CH[i]>=2 and CW[j]>=2:
        CH[i]-=2
        CW[j]-=2
        continue

    if CH[i]<2:
        i+=1
    if CW[j]<2:
        j+=1

print(sum(CH))