n = int(input())

arr = []
for _ in range(n):
    r, g = list(map(int, input().split()))
    arr.append((r, r + g))

i = 1

while True:
    ok = True
    for r, p in arr:
        if i % p < r:
            ok = False
    if ok:
        print(i)
        break

    i += 1