import math

t = int(input().strip()) num = [0] * 50

for i in range(t): a, b = map(lambda x: float(x.strip()), input().split()) b = int(b) for j in range(1, b+1): x = math.floor(a * j) num[x] += 1

count = 0 for i in num: if i % 2 == 1: count = i break

print(num.index(count))