func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m;   int a[100005];   int tr[100005];   int lb(int x) { return x & (-x); }   void add(int x, int v) {     while (x <= 100000) {       tr[x] = max(tr[x], v);       x += lb(x);     }   }   int get(int x) {     int ans = 0;     while (x > 0) {       ans = max(ans, tr[x]);       x -= lb(x);     }     return ans;   }   int ans1[100005];   int ans2[100005];   int main() {     while (~scanf( %d%d , &n, &m)) {       memset(a, 0, sizeof(a));       memset(tr, 0, sizeof(tr));       for (int i = 0; i < n; i++) {         int l, r;         scanf( %d%d , &l, &r);         a[l]++;         a[r + 1]--;       }       for (int i = 2; i <= m; i++) {         a[i] += a[i - 1];       }       for (int i = 1; i <= m; i++) a[i]++;       for (int i = 1; i <= m; i++) {         ans1[i] = get(a[i]) + 1;         add(a[i], ans1[i]);       }       memset(tr, 0, sizeof(tr));       for (int i = m; i >= 1; i--) {         ans2[i] = get(a[i]) + 1;         add(a[i], ans2[i]);       }       int ans = 0;       for (int i = 1; i <= m; i++) {         ans = max(ans, ans1[i] + ans2[i] - 1);       }       printf( %d n , ans);     }     return 0;   }   