n,m=map(int,input().split())
ALIST=[]

for i in range(m):
    A=[list(map(int,input().split())) for i in range(n)]

    LIST=[]

    for j in range(n):
        X=A[j][:]
        LIST.append(X)

    for j in range(n):
        X=[]
        for k in range(n):
            X.append(A[k][j])
        LIST.append(X)

    X=[]
    for j in range(n):
        X.append(A[j][j])
    LIST.append(X)

    X=[]
    for j in range(n):
        X.append(A[n-1-j][j])
    LIST.append(X)

    ALIST.append(LIST)

MIN=1<<60

for i in range(m):
    for p in ALIST[i]:
        for j in range(i+1,m):
            for q in ALIST[j]:
                MIN=min(MIN,len(set(p+q)))

print(MIN-1)