n = int(input())
P = [list(map(int, input().split())) + [i + 1] for i in range(n)]

P.sort(key=lambda x: (x[0], x[1]))
ANS = []
seen = set()
for i in range(n):
    cx, cy, idx = P[i]
    if idx in seen:
        continue
    d = 10**18
    res = None
    for j in range(n):
        nx, ny, nidx = P[j]
        if idx == nidx or nidx in seen:
            continue
        if (nx - cx)**2 + (ny - cy)**2 < d:
            d = (nx - cx)**2 + (ny - cy)**2
            res = nidx
    if res is not None:
        ANS.append((idx, res))
        seen.add(idx)
        seen.add(res)
print(len(ANS))
for ans in ANS:
    print(*ans)