#include <bits/stdc++.h>
using namespace std;
int main()
{
int v[10010];
//vector<int>v;
int i,j,n,k,max,price1,a,price2,m,diff,tmp;
while(cin>>n)
{
for(i=0;i<n;i++)
cin>>v[i];
//v.push_back(i);
cin>>m;
max=1000000;
for(i=0;i<n-1;i++)
for(j=i+1;j<n;j++)
{
if((v[i]+v[j])== m)
{
diff=abs(v[i]-v[j]);
if(diff<max)
{
max=diff;
price1=v[i];
price2=v[j];
}
}
}
if(price1>price2)
{
tmp=price1;
price1=price2;
price2=tmp;
}
printf("Peter should buy books whose prices are %d and %d.\n\n",price1,price2);
}
return 0;
}
