n = int(input())
road = []
for x in range(n):
    a, t = map(eval, input().split(' '))
    light = [1 for _ in range(int(a * t))]
    if x != 0:
        for k in range(int(a * t)):
            try:
                light[k] = road[k]
            except IndexError:
                pass
    for i in range(1, t + 1):
        if light[int(i * a) - 1] == 1:
            light[int(i * a) - 1] = 0
        else:
            light[int(i * a) - 1] = 1
    for j in range(int(a * t)):
        try:
            road[j] = light[j]
        except IndexError:
            road.append(light[j])
print(road.index(0) + 1)

rt，问题可能出在灯状态的存储？还请多多指教！