Equation - MarisaOJ: Marisa Online Judge

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Find the number of positive integers solutions

$(x_1, x_2,..., x_k)$ for the following equation:

$\begin{equation} \begin{cases} x_1 < x_2 < ... < x_k \\\\ x_1 + x_2 + ... + x_k=n \end{cases} \end{equation}$ ### Input - A single line contains two integers

$n, k$ . ### Output - Print the number of solutions, modulo

$10^9+7$ . ### Constraints -

$1 \le n \le 10^9$ . -

$1 \le k \le 5$ . ### Example Input:

$10 3$

Output:

$4$

Digit DP
	Unlucky number
	Digit Sum
	Divisible
	Prime digit sum
	Non-palindrome number
	Yet another XOR problem
	Taboo substring
	Balanced number
	Equation
	Beautiful number
	Constructing numbers

Topic

Dynamic Programming

Rating

2100

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