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문제

Let us consider the set of integer numbers between 1 and N inclusive. Let us order them lexicographically (i. e. like in the vocabulary), for example, for N = 11 the order would be: 1, 10, 11, 2, 3, 4, 5, 6, 7, 8, 9.

Let us denote the position of the number K in this ordering as QN,K. For example, Q11,2 = 4. Given numbers K and M find the smallest N such that QN,K = M.

입력

Input contains two integer numbers K and M (1 ≤ K, M ≤ 109) separated by a space.

출력

If such N that QN,K = M exists then write to the output file the smallest such N, otherwise write 0.

예제 입력 1

2 4

예제 출력 1

11

예제 입력 2

2 1

예제 출력 2

0

예제 입력 3

100000001 1000000000

예제 출력 3

100000000888888879

예제 입력 4

1000000000 11

예제 출력 4

0