func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 5e5 + 5;   int nxt[maxn];   int n, ans, m, l, r;   int rmq[maxn][30];   int main() {     ios::sync_with_stdio(false);     cin >> n >> m;     for (int i = 1; i <= n; i++) {       cin >> l >> r;       nxt[l] = max(nxt[l], r);     }     for (int i = 0; i < maxn; i++) {       nxt[i] = max(nxt[i], nxt[i - 1]);       nxt[i] = max(nxt[i], i);       rmq[i][0] = nxt[i];     }     for (int i = 1; i <= 25; i++)       for (int j = 0; j < maxn; j++) {         rmq[j][i] = max(rmq[j][i - 1], rmq[rmq[j][i - 1]][i - 1]);       }     for (int i = 1; i <= m; i++) {       cin >> l >> r;       ans = 0;       for (int j = 25; j >= 0; j--) {         if (rmq[l][j] < r) {           l = rmq[l][j];           ans = ans + (1 << j);         }       }       if (l < r) {         l = rmq[l][0];         ans++;       }       if (l >= r)         cout << ans <<   n ;       else         cout << -1 <<   n ;     }   }   