#include <stdio.h> #include <algorithm> using namespace std; const double inf = 1e9; int n; struct P { double x, y, g; int idx; } p[999]; inline bool cmp(P a, P b) { return a.g < b.g; } int main() { scanf("%d", &n); for (int i = 1; i <= 3 * n; i++) { scanf("%lf%lf", &p[i].x, &p[i].y); p[i].g = (p[i].y - inf) / (p[i].x - 2 * inf); p[i].idx = i; } sort(p + 1, p + 3 * n + 1, cmp); for (int i = 1; i <= 3 * n; i += 3) printf("%d %d %d\n", p[i].idx, p[i + 1].idx, p[i + 2].idx); }