c = int(input())

vectors = []

for i in range(0, c):
    line = input()
    split = line.split()
    vectors.append((int(split[0]), int(split[1])))

def to_zero(vector: tuple):
    sub = min(vector[0], vector[1])
    return vector[0] - sub, vector[1] - sub

def filter_vectors(zero: tuple):
    count = 0
    for v in vectors:
        if to_zero(v) == zero:
            #vectors.remove(v)
            count += 1

    if count > 1:
        shift_vectors.add(zero)

count = 0
shift_vectors = set()

for v in vectors:
    filter_vectors(to_zero(v))
    count += 1

#print(shift_vectors)
print(len(shift_vectors))