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from collections import Counter
def comb2(n):
    return int(n*(n-1)/2)
n = int(raw_input())
queen_loc = []
for i in range(n):
    queen_loc.append([int(s) for s in raw_input().split(' ')])
R, C, LD, RD = [], [], [], []
# in same row, column, right diagonal and left diagonal
for loc in queen_loc:
    r_i , c_i = loc
    R.append(r_i)
    C.append(c_i)
    LD.append(r_i+c_i)
    RD.append(r_i-c_i)
sum_queen = 0
for cat in [Counter(R),Counter(C),Counter(LD),Counter(RD)]:
    for item in cat.values():
        if item > 1:
            sum_queen += comb2(item)
print(int(sum_queen))
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