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  1. #include <bits/stdc++.h>
  2. #define ll long long
  3. #define fi first
  4. #define se second
  5. #define el '\n'
  6. #define pback push_back
  7. #define pii pair <int, int>
  8. #define plli pair <ll, int>
  9. #define pill pair <int, ll>
  10. #define pllll pair <ll, ll>
  11. #define FOR(i, a, b) for (int i = a; i <= b; ++i)
  12. #define FORD(i, a, b) for (int i = a; i >= b; --i)
  13.  
  14. using namespace std;
  15.  
  16. const int N = 2e5 + 5;
  17. const ll MOD = 1e9 + 7;
  18. const ll MOD1 = 998244353;
  19. const int MASK = (1 << 20);
  20. const int base = 256;
  21. const int BL = 447;
  22.  
  23. int n, q;
  24. ll f[N], g[N];
  25.  
  26. void input() {
  27. cin >> n >> q;
  28. while (q--) {
  29. int l, r;
  30. cin >> l >> r;
  31. f[l]++;
  32. f[r + 1]--;
  33. //
  34. g[l] += 1 - l;
  35. g[r + 1] -= (1 - l);
  36. }
  37. ll res = 0;
  38. FOR(i, 1, n) {
  39. f[i] += f[i - 1];
  40. g[i] += g[i - 1];
  41. ll val = 1ll * f[i] * i + g[i];
  42. res = max(res, val);
  43. }
  44. cout << res;
  45. }
  46.  
  47. signed main()
  48. {
  49. #define name "task"
  50. ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  51. if (fopen(name".inp", "r")) {
  52. freopen(name".inp", "r", stdin);
  53. freopen(name".ans", "w", stdout);
  54. }
  55. //
  56. input();
  57. //cerr << "Time elapsed: " << (1.0 * clock() / CLOCKS_PER_SEC) << "s";
  58. return 0;
  59. }
  60.  
Success #stdin #stdout 0s 5308KB
stdin
Standard input is empty
stdout
Standard output is empty