#include <any> #include <iostream> #include <vector> #include <algorithm> using namespace std; int main() { int l, m; cin >> l >> m; vector<pair<int, int>> v(m); for (int i = 0; i < m; ++i) { cin >> v[i].first >> v[i].second; } sort(v.begin(), v.end()); vector<pair<int, int>> tmp; for (const auto& kv : v) { if (tmp.empty() || tmp.back().second < kv.first - 1) { tmp.push_back(kv); } else { tmp.back().second = max(tmp.back().second, kv.second); } } int ret = l + 1; for (const auto& kv : tmp) { ret -= (kv.second - kv.first + 1); } cout << ret << endl; }