n = int(input())

a = []
for _ in range(n):
    u, v = map(int, input().split())
    a.append((u, v))

ti = 1
while True:
    green = 0
    for u, v in a:
        tot = u+v;
        if (ti%tot) >= u:
            green += 1
    if green == n:
        break
    ti += 1
print(ti)