#include<stdio.h>
#include<algorithm>
using namespace std;
FILE*f=fopen("infasuratoare.in","r");
FILE*g=fopen("infasuratoare.out","w");
double minx,miny;
int n,j,i,poz,stv[120001],k;
struct punct{
	double x;
	double y;
	double ctg;
} v[120001];
int cmp(punct a,punct b){
	return a.ctg>b.ctg;
}
int ver(int P1,int P2,int P3){
	long double A, X1, Y1, X2, Y2, X3, Y3;
   
    X1 = v[P1].x, Y1 = v[P1].y, X2 = v[P2].x, Y2 = v[P2].y, X3 = v[P3].x, Y3 = v[P3].y;
    A = (X3 - X2) * (Y1 - Y2) - (X1 - X2) * (Y3 - Y2);
     
    if (A > 0)
        return 1;
    return 0;
/*
	if(v[i2].x*(long double)v[i3].y+v[i1].x*(long double)v[i2].y+v[i3].x*(long double)v[i1].y
		>(long double)v[i2].x*v[i1].y+(long double)v[i1].x*v[i3].y+(long double)v[i3].x*v[i2].y)
		return 1;
	else
		return 0;
*/
}
int main() {
	fscanf(f,"%d",&n);
	miny=1LL<<62;
	for(i=1;i<=n;++i){
		fscanf(f,"%lf%lf",&v[i].x,&v[i].y);
		if(miny>v[i].y){
			miny=v[i].y;
			minx=v[i].x;
			poz=i;
		}
	}
	v[poz].x=v[1].x;
	v[poz].y=v[1].y;
	v[1].x=v[1].y=0;
	v[1].ctg=0;
	for(i=2;i<=n;++i){
		v[i].x-=minx;
		v[i].y-=miny;
		v[i].ctg=v[i].x/v[i].y;
	}
	
	
	sort(v+2,v+n+1,cmp);
	
	stv[1]=1;
	stv[2]=2;
	k=2;
	
	for(i=3;i<=n;++i){
		while(!ver(stv[k-1],stv[k],i) && k>2){
			k--;
		}
		stv[++k]=i;
	}
	
	fprintf(g,"%d\n",k);
	
	for(i=1;i<=k;++i)
		fprintf(g,"%lf %lf\n",v[stv[i]].x+minx,v[stv[i]].y+miny);
	fclose(g);
	fclose(f);
	return 0;
}