#include<iostream>
#include<math.h>
using namespace std;
int main()
{
    long long n,p,a=1;
    cin>>n;
    while(1)
    {
        p=(1-2*a+sqrt((2*a-1)*(2*a-1)+8*n))/2;
        if(2*n==2*p*a+p*(p-1))
        {
            cout<<a<<" "<<p;
            break;
        }
        a++;
    }
    return 0;
}

On test #9 my solution got the same problem.

Edited by author 14.11.2015 14:30