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#include <iostream>
using namespace std;
const int N = 1e6+10;
int l[N],r[N];
void dfs1(int root)
{if(!root) return;cout << root << " ";dfs1(l[root]);dfs1(r[root]);}
void dfs2(int root)
{if(!root) return;dfs2(l[root]);cout << root << " ";dfs2(r[root]);
}
void dfs3(int root)
{if(!root) return;dfs3(l[root]);dfs3(r[root]);cout << root << " ";
}
int main()
{int n;cin >> n;for(int i = 1;i<=n;i++){cin >> l[i] >> r[i];}dfs1(1);cout << endl;dfs2(1);cout << endl;dfs3(1);cout << endl;return 0;
}