#include<fstream>
using namespace std;
ifstream f("onu.in");
ofstream g("onu.out");
int n,i,a[100001],b[100001];
int main()
{f>>n;
for (i=1;i<=2*n;i++)
	{f>>a[i];
	b[1]=1;
	if (a[i]!=a[i-1])
		if (b[i-1]==1)
			b[i]=2;
		else
			{b[i]=1;
			g<<i<<" ";}
	else
		if (b[i-2]==b[i-1])
			if (b[i-1]==1)
			b[i]=2;
		else
			{b[i]=1;
			g<<i<<" ";}
	}
g<<'\n';
for (i=1;i<=2*n;i++)
	if (b[i]==2)
		g<<i<<" ";
g<<'\n';
f.close();
g.close();
return 0;
}