import sys
input = sys.stdin.readline

N, M = map(int, input().split())
S_list = [[] for _ in range(M)]

for i in range(M):
    C = [list(map(int, input().split())) for _ in range(N)]
    
    for j in range(N):
        s = set()
        
        for k in range(N):
            s.add(C[j][k])
        
        S_list[i].append(s)
    
    for j in range(N):
        s = set()
        
        for k in range(N):
            s.add(C[k][j])
        
        S_list[i].append(s)
    
    s = set()
    
    for j in range(N):
        s.add(C[j][j])
    
    S_list[i].append(s)
    
    s = set()
    
    for j in range(N):
        s.add(C[N-1-j][j])
    
    S_list[i].append(s)

max_same = 0

for i in range(M):
    for j in range(i+1, M):
        for k in range(2*N+2):
            for l in range(2*N+2):
                max_same = max(max_same, len(S_list[i][k]&S_list[j][l]))

print(2*N-max_same-1)