import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(1000005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# md = 10**9+7
md = 998244353

def outer(x,y,p,q,s,t):
    return (s-x)*(q-y)-(t-y)*(p-x)

n = II()
xy = []
for i in range(n):
    x, y = LI()
    xy.append((x, y, i))
xy.sort()
fin = [0]*n

ans = []
for p, (x, y, i) in enumerate(xy):
    if fin[p]:continue
    q=p+1
    while q<n and fin[q]:q+=1
    if q==n:break
    a,b,_=xy[q]
    for r in range(q+1,n):
        if fin[r]:continue
        c,d,_=xy[r]
        if outer(x,y,a,b,c,d)>0:
            a,b,q=c,d,r
    j=xy[q][2]
    ans.append((i+1,j+1))
    fin[p]=1
    fin[q]=1

print(len(ans))
for i,j in ans:print(i,j)