#include<bits/stdc++.h>
// #define int long long
#define INF 0x3f3f3f3f
#define mod 1000000007
#define MOD 998244353
#define rep(i, st, ed) for (int (i) = (st); (i) <= (ed);++(i))
#define pre(i, ed, st) for (int (i) = (ed); (i) >= (st);--(i))
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int, int> PII;
template<typename T> inline T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }
template<typename T> inline T lowbit(T x) { return x & -x; }
const int N = 1e3 + 10;
int a[N][5 * N], dp[N][5 * N];
bool vis[N][5 * N];
int n, k;
void solve() {
  cin >> k >> n;
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= k; ++j) {
      cin >> a[i][j];
      vis[i][a[i][j]] = true;
    }
  }
  int maxn = 0;
  for (int i = 1; i <= n; ++i) {
    maxn = 0;
    for (int j = 1; j <= 1000; ++j) {
      if (vis[i][j]) {
        dp[i][j] = max(dp[i][j], maxn + 1);
      }
      else dp[i][j] = dp[i - 1][j];
      maxn = max(maxn, dp[i - 1][j]);
    }
  }
  int res = 0;
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= 1000; ++j) {
      res = max(res, dp[i][j]);
    }
  }
  cout << res << endl;
}
signed main() {
  // int t; cin >> t;
  // while (t--)
    solve();
  return 0;
}