This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define ar array
#define pb push_back
#define ln '\n'
#define int long long
using i64 = long long;
template <class F, class _S>
bool chmin(F &u, const _S &v){
bool flag = false;
if ( u > v ){
u = v; flag |= true;
}
return flag;
}
template <class F, class _S>
bool chmax(F &u, const _S &v){
bool flag = false;
if ( u < v ){
u = v; flag |= true;
}
return flag;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n; cin >> n;
vector <int> L(n), R(n);
for ( int i = 0; i < n; i++ ){
cin >> L[i] >> R[i];
--L[i], --R[i];
}
int qq; cin >> qq;
while ( qq-- ){
int s; cin >> s;
--s;
if ( !s ){
int ans = 0, lst = -1;
bool flag = true;
priority_queue <int> q;
q.push(R[s]);
for ( int i = 1; i < n; i++ ){
if ( lst < i ){
if ( q.empty() || q.top() < i ){
flag = false;
break;
}
lst = q.top();
q.pop(); ++ans;
} q.push(R[i]);
}
cout << (flag ? ans : -1) << ln;
continue;
}
const int inf = 1e15;
vector <vector<int>> dp(n, vector <int> (n, inf));
dp[L[s]][R[s]] = 1;
queue <ar<int,2>> q;
q.push({L[s], R[s]});
while ( !q.empty() ){
auto [u, v] = q.front();
q.pop();
for ( int j = u; j <= v; j++ ){
int x = min(u, L[j]), y = max(v, R[j]);
if ( chmin(dp[x][y], dp[u][v] + 1) ){
q.push({x, y});
}
}
}
int ans = dp[0][n - 1];
if ( ans == inf ){
ans = -1;
}
cout << ans << ln;
}
cout << '\n';
}
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