#include <fstream>
#include <stack>
#include <algorithm>
#define NMAX 120001

using namespace std;
ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");
struct Punct
{
    double x,y;
    friend bool operator <(Punct a,Punct b);

};
int n,i;
Punct P,V[NMAX];
stack <Punct>S;
bool operator<(Punct a, Punct b)
{
    return (a.y-P.y)*(b.x-P.x)<(a.x-P.x)*(b.y-P.y);
}
void citire();
int main()
{
    citire();
    sort(V,V+n);
    S.push(V[0]);
    for(i=1;i<n;i++)//analizez vf stivei cu V[i] si V[i+1]
    {
        if(arie(S.top(),V[i],V[i+1])<=0)
      while(!S.empty())
        {
            V[i]=S.top();
            S.pop();
             if(arie(S.top(),V[i],V[i+1])>0) break;

         }
         S.push(V[i]);
    }
    //afisare
    return 0;
}
void citire()
{   int i;
    fin>>n;
    fin>>V[0].x>>V[0].y;
    P=V[0];
    for(i=0;i<=n;i++)
    {
        fin>>V[i].x>>V[i].y;
        if(V[i].x<P.x||V[i].x==P.x&&V[i].y<P.y)
            P=V[i];
    }
    V[n]=V[0];
}