#include <fstream>

using namespace std;
ifstream f("jack.in");
ofstream g("jack.out");

int main()
{
    int x,i=1,sum=0;
    f>>x;
    if(x==0) g<<0;
    else if(x==1) g<<2;
    else if(x==2) g<<3;
    else
    {
    while(i*(i+1)/2<x)
        i++;
    sum=i*(i+1)/2;
    if(sum%2==x%2)
        g<<i;
    else if((sum+i+1)%2==x%2) g<<i+1;
    else
    {
        while((sum+i+1)%2!=x%2)
            i++;
    }
    }

    return 0;
}