#include<bits/stdc++.h>
#include "popa.h"
#define st first
#define nd second
#define pb push_back
#define ppb pop_back
#define umax(x,y) x=max(x,y)
#define umin(x,y) x=min(x,y)
#define ll long long
#define ii pair<int,int>
#define iii pair<ii,int>
#define sz(x) (x.size())
#define orta ((bas+son)>>1)
#define all(x) x.begin(),x.end()
#define dbgs(x) cerr<<(#x)<<" --> "<<(x)<<" "
#define dbg(x) cerr<<(#x)<<" --> "<<(x)<<endl;getchar()
#define pw(x) (1<<(x))
#define inf 1000500000
#define MOD 1000000007
//#define N 3005
#define MAX 10000006
#define LOG 20
using namespace std;
int solve(int N,int *Left,int *Right) {
stack<int> s;
int head=0;
for(int i=0;i<N;i++) {
Left[i]=Right[i]=-1;
while(sz(s) && query(s.top(),i,i,i)) {
Right[s.top()]=Left[i];
Left[i]=s.top();
s.pop();
}
if(sz(s)) {
Right[s.top()]=i;
}
else {
head=i;
}
s.push(i);
}
return head;
}
