func_code_string: #include <bits/stdc++.h>   using namespace std;   template <typename Arg1>   void __f(const char* name, Arg1&& arg1) {     cerr << name <<   :   << arg1 << std::endl;   }   template <typename Arg1, typename... Args>   void __f(const char* names, Arg1&& arg1, Args&&... args) {     const char* comma = strchr(names + 1,  , );     cerr.write(names, comma - names) <<   :   << arg1 <<   |  ;     __f(comma + 1, args...);   }   vector<int> val[100010];   int x[100010];   int td[100010 * 4], ti[100010 * 4];   int queryd(int node, int lo, int hi, int l, int r) {     if (l > hi or r < lo) return 0;     if (lo >= l and hi <= r) return td[node];     int md = (lo + hi) >> 1;     int p1 = queryd(node << 1, lo, md, l, r);     int p2 = queryd(node << 1 | 1, md + 1, hi, l, r);     return max(p1, p2);   }   void updated(int node, int lo, int hi, int idx, int val) {     if (lo == hi) {       td[node] = max(td[node], val);       return;     }     int md = (lo + hi) >> 1;     if (idx <= md)       updated(node << 1, lo, md, idx, val);     else       updated(node << 1 | 1, md + 1, hi, idx, val);     td[node] = max(td[node << 1], td[node << 1 | 1]);   }   int queryi(int node, int lo, int hi, int l, int r) {     if (l > hi or r < lo) return 0;     if (lo >= l and hi <= r) return ti[node];     int md = (lo + hi) >> 1;     int p1 = queryi(node << 1, lo, md, l, r);     int p2 = queryi(node << 1 | 1, md + 1, hi, l, r);     return max(p1, p2);   }   void updatei(int node, int lo, int hi, int idx, int val) {     if (lo == hi) {       ti[node] = max(ti[node], val);       return;     }     int md = (lo + hi) >> 1;     if (idx <= md)       updatei(node << 1, lo, md, idx, val);     else       updatei(node << 1 | 1, md + 1, hi, idx, val);     ti[node] = max(ti[node << 1], ti[node << 1 | 1]);   }   int ai[100010], ad[100010], md[100010];   int main() {     int n, m;     cin >> n >> m;     for (int i = 0, l, r; i < n; ++i) {       cin >> l >> r;       x[l]++;       x[r + 1]--;     }     for (int i = 1; i <= m; ++i) {       x[i] += x[i - 1];     }     for (int i = 1; i <= m; ++i) {       auto xz = queryi(1, 0, n, 0, x[i]);       ai[i] = xz + 1;       updatei(1, 0, n, x[i], xz + 1);     }     for (int i = m; i > 0; --i) {       auto xz = queryd(1, 0, n, 0, x[i]);       ad[i] = xz + 1;       updated(1, 0, n, x[i], xz + 1);     }     md[m] = ad[m];     int ans = 0;     for (int i = m - 1; i > 0; --i) {       md[i] = max(ad[i], md[i + 1]);     }     for (int i = 1; i < m; ++i) {       ans = max(ans, ai[i] + md[i + 1]);     }     cout << ans << endl;   }   