func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 600005;   int n, m, l, r, ma, a[N], f[N][22];   int main() {     scanf( %d%d , &n, &m);     for (int i = 1; i <= n; i++) {       scanf( %d%d , &l, &r);       a[l] = max(a[l], r);       ma = max(ma, r);     }     for (int i = 1; i <= ma; i++) a[i] = max(a[i], a[i - 1]);     for (int i = 0; i <= ma; i++) f[i][0] = a[i];     for (int i = 1; i <= 20; i++)       for (int j = 0; j <= ma; j++) f[j][i] = f[f[j][i - 1]][i - 1];     while (m--) {       cin >> l >> r;       int ans = 0;       for (int i = 20; i >= 0; i--)         if (f[l][i] < r) {           ans += 1 << i;           l = f[l][i];         }       if (a[l] >= r)         printf( %d n , ans + 1);       else         cout << -1 <<   n ;     }     return 0;   }   