#yukicoder 187 中華風(Hard)  多倍長解法

#exec gcd
#Reference: https://x.com/_miz_tom/status/1842086118990479854
exec('def gcd(x, y):\n' +
     ' x, y = abs(x), abs(y)\n' +
     ' if x == 0: return y\n' +
     ' if not (y := y % x): return x\n if not (x := x % y): return y\n' * 300 +
     ' return gcd(x, y)')
def CRT(n1, M1, n2, M2):  #smallest n mod M ≡ n1 mod M1 ≡ n2 mod M2
    if (n1 - n2) % ( G := gcd(M1, M2) ) != 0: return (0, 0)
    return ( (n1 - n2) * pow( c := M2 // G, -1, M1 // G) % M1 * M2 // G + n2, M1 * c )


#入力受取
N = int(input())
P = [tuple(map(int, input().split())) for _ in range(N)]
MOD = 10 ** 9 + 7

#CRTを実行
rem, mod = 0, 1
for Xi, Yi in P:
    rem, mod = CRT(rem, mod, Xi, Yi)
    if mod == 0:
        break

if   mod == 0:  #解なし
    print(-1)
elif rem == 0:  #正整数を探す → lcm(Yi)
    print(mod % MOD)
else:  #remを出力
    print(rem % MOD)