from decimal import Decimal
from collections import defaultdict
from bisect import bisect_left, bisect_right

N = int(input())
XY = [list(map(int, input().split())) for _ in range(N)]

def vec(a, b):
    return (b[0]-a[0], b[1]-a[1])

D1 = defaultdict(list)
D2 = defaultdict(list)
for i in range(N-1):
    X1, Y1 = XY[i]
    for j in range(i+1, N):
        X2, Y2 = XY[j]
        if Y1 == Y2:
            center = (Decimal(X1)+Decimal(X2))/2
            D1[(center, Y1)].append(0)
        else:
            x1, y1, x2, y2 = X1, Y1, X2, Y2
            if y2 < y1:
                x1, y1, x2, y2 = x2, y2, x1, y1
            if x1 == x2:
                center = (Decimal(y1)+Decimal(y2))/2
                D2[(x1, center)].append(0)
            else:
                cX = (Decimal(x1)+Decimal(x2))/2
                cY = (Decimal(y1)+Decimal(y2))/2
                if x1 < x2:
                    vX, vY = vec((x1, y1), (x2, y2))
                    V = Decimal(vX)/Decimal(vY)
                    D1[(cX, cY)].append(V)
                else:
                    vX, vY = vec((y1, -x1), (y2, -x2))
                    V = Decimal(vX)/Decimal(vY)
                    D2[(cX, cY)].append(V)

for k in D2.keys():
    D2[k].sort()

ans = 0
for k in D1.keys():
    if k in D2:
        for i in D1[k]:
            ans += bisect_right(D2[k], i)-bisect_left(D2[k], i)

print(ans)