#include <bits/stdc++.h> using namespace std; using ll = long long; int main() { ios::sync_with_stdio(false); cin.tie(nullptr); ll L; int R; if (!(cin >> L >> R)) return 0; vector<pair<ll,ll>> global_unavoidable; global_unavoidable.reserve(1000); for (int ri = 0; ri < R; ++ri) { int t; cin >> t; vector<ll> ps; ps.reserve(t + 1); ps.push_back(0); for (int j = 0; j < t; ++j) { ll w; cin >> w; ps.push_back(ps.back() + w); } ll S = ps.back(); if (S == L) { // This row forces all lasers cout << L << '\n'; return 0; } ll F = L - S; if (F <= 0) { // no free space (S >= L handled above), but guard global_unavoidable.emplace_back(1, L); continue; } // Build avoidable intervals [x+1, x+F] for each prefix x in ps vector<pair<ll,ll>> avoid; avoid.reserve(ps.size()); for (ll x : ps) { ll l = x + 1; ll r = x + F; if (l > L || r < 1) continue; if (l < 1) l = 1; if (r > L) r = L; if (l <= r) avoid.emplace_back(l, r); } if (avoid.empty()) { // Nothing avoidable -> whole [1..L] unavoidable global_unavoidable.emplace_back(1, L); continue; } // Merge avoidable intervals (they are in increasing left order because ps is increasing) vector<pair<ll,ll>> merged_avoid; merged_avoid.reserve(avoid.size()); for (size_t i = 0; i < avoid.size(); ++i) { ll l = avoid[i].first; ll r = avoid[i].second; if (merged_avoid.empty() || merged_avoid.back().second + 1 < l) { merged_avoid.emplace_back(l, r); } else { if (r > merged_avoid.back().second) merged_avoid.back().second = r; } } // Complement of merged_avoid inside [1..L] -> unavoidable intervals for this row ll cur = 1; for (size_t i = 0; i < merged_avoid.size(); ++i) { ll l = merged_avoid[i].first; ll r = merged_avoid[i].second; if (cur < l) { global_unavoidable.emplace_back(cur, l - 1); } cur = r + 1; if (cur > L) break; } if (cur <= L) { global_unavoidable.emplace_back(cur, L); } } if (global_unavoidable.empty()) { cout << 0 << '\n'; return 0; } // Merge global unavoidable intervals sort(global_unavoidable.begin(), global_unavoidable.end()); ll ans = 0; pair<ll,ll> cur = global_unavoidable[0]; for (size_t i = 1; i < global_unavoidable.size(); ++i) { pair<ll,ll> iv = global_unavoidable[i]; if (cur.second + 1 < iv.first) { ans += (cur.second - cur.first + 1); cur = iv; } else { if (iv.second > cur.second) cur.second = iv.second; } } ans += (cur.second - cur.first + 1); if (ans > L) ans = L; cout << ans << '\n'; return 0; }