A positive integer is magical if it is divisible by either a or b. Given the three integers n, a, and b, return the nth magical number. Since the answer may be very large, return it modulo 109 + 7. Example 1: Input: n = 1, a = 2, b = 3 Output: 2 Example 2: Input: n = 4, a = 2, b = 3 Output: 6 Example 3: Input: n = 5, a = 2, b = 4 Output: 10 Example 4: Input: n = 3, a = 6, b = 4 Output: 8 Constraints: 1 <= n <= 109 2 <= a, b <= 4 * 104