Problem Statement

There are an integer sequence A_1,...,A_N consisting of N terms, and N buttons. When the i-th (1 ≦ i ≦ N) button is pressed, the values of the i terms from the first through the i-th are all incremented by 1.

There is also another integer sequence B_1,...,B_N. Takahashi will push the buttons some number of times so that for every i, A_i will be a multiple of B_i.

Find the minimum number of times Takahashi will press the buttons.

Constraints

• All input values are integers.
• 1 ≦ N ≦ 10^5
• 0 ≦ A_i ≦ 10^9(1 ≦ i ≦ N)
• 1 ≦ B_i ≦ 10^9(1 ≦ i ≦ N)

Sample Input 1

3
3 5
2 7
9 4

Sample Output 1

7

Press the first button twice, the second button twice and the third button three times.

Sample Input 2

7
3 1
4 1
5 9
2 6
5 3
5 8
9 7

Sample Output 2

22