#include <bits/stdc++.h>
// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2")
int32_t solve(int n, int m, std::vector<int> f, std::vector<std::vector<int>> s) {
#define all(a) a.begin(), a.end()
#define int int64_t
using namespace std;
const int INF = 1e12;
mt19937 rnd(1488);
vector<int> hsh(n);
for (int i = 1; i < n; i++)
hsh[i] = rnd();
vector<int> ph1(n), penis(n);
for (int i = 0; i + 1 < n; i++) {
int cur_val = 0;
for (int j = 0; j < m; j++)
cur_val += hsh[s[j][i]];
ph1[i + 1] = cur_val + ph1[i];
cur_val = 0;
for (int j = 0; j < m; j++)
cur_val += hsh[s[0][i]];
penis[i + 1] = cur_val + penis[i];
}
vector<int> dp(n, -INF);
dp[0] = 0;
for (int i = 1; i < n; i++) {
for (int j = 0; j < i; j++) {
if (ph1[i] - ph1[j] == penis[i] - penis[j])
dp[i] = max(dp[i], dp[j] + 1);
}
}
return dp[n - 1];
}
// int32_t main() {
// using namespace std;
// int n, m; cin >> n >> m;
// vector<int32_t> f(n);
// vector<vector<int32_t>> s(m, vector<int32_t>(n - 1));
// for (int32_t &i : f)
// cin >> i;
// for (auto &i : s)
// for (auto &j : i)
// cin >> j;
// cout << solve(n, m, f, s);
// }
