11057 - Exact Sum

#include <stdio.h>
#include <algorithm>
using namespace std;

int main()
{
    for(int n; ~scanf("%d", &n);)
    {
        int arr[n], m, a, b;

        for(int i=0; i<n; i++)
            scanf("%d", arr+i);

        scanf("%d", &m);
        sort(arr, arr+n);

        for(int i=0; arr[i]*2<=m && i<n; i++)
        {
            int tmp=*lower_bound(arr+i+1, arr+n, m-arr[i]);

            if(tmp==m-arr[i])
                a=arr[i], b=tmp;
        }
        printf("Peter should buy books whose prices are %d and %d.\n\n", a, b);
    }
}