#D4339. Alternating Sum
Alternating Sum
Alternating Sum
You are given two integers a and b. Moreover, you are given a sequence s_0, s_1, ..., s_{n}. All values in s are integers 1 or -1. It's known that sequence is k-periodic and k divides n+1. In other words, for each k ≤ i ≤ n it's satisfied that s_{i} = s_{i - k}.
Find out the non-negative remainder of division of ∑ {i=0}^{n} s{i} a^{n - i} b^{i} by 10^{9} + 9.
Note that the modulo is unusual!
Input
The first line contains four integers n, a, b and k (1 ≤ n ≤ 10^{9}, 1 ≤ a, b ≤ 10^{9}, 1 ≤ k ≤ 10^{5}).
The second line contains a sequence of length k consisting of characters '+' and '-'.
If the i-th character (0-indexed) is '+', then s_{i} = 1, otherwise s_{i} = -1.
Note that only the first k members of the sequence are given, the rest can be obtained using the periodicity property.
Output
Output a single integer — value of given expression modulo 10^{9} + 9.
Examples
Input
2 2 3 3 +-+
Output
7
Input
4 1 5 1
Output
999999228
Note
In the first example:
(∑ {i=0}^{n} s{i} a^{n - i} b^{i}) = 2^{2} 3^{0} - 2^{1} 3^{1} + 2^{0} 3^{2} = 7
In the second example:
(∑ {i=0}^{n} s{i} a^{n - i} b^{i}) = -1^{4} 5^{0} - 1^{3} 5^{1} - 1^{2} 5^{2} - 1^{1} 5^{3} - 1^{0} 5^{4} = -781 ≡ 999999228 \pmod{10^{9} + 9}.
inputFormat
Input
The first line contains four integers n, a, b and k (1 ≤ n ≤ 10^{9}, 1 ≤ a, b ≤ 10^{9}, 1 ≤ k ≤ 10^{5}).
The second line contains a sequence of length k consisting of characters '+' and '-'.
If the i-th character (0-indexed) is '+', then s_{i} = 1, otherwise s_{i} = -1.
Note that only the first k members of the sequence are given, the rest can be obtained using the periodicity property.
outputFormat
Output
Output a single integer — value of given expression modulo 10^{9} + 9.
Examples
Input
2 2 3 3 +-+
Output
7
Input
4 1 5 1
Output
999999228
Note
In the first example:
(∑ {i=0}^{n} s{i} a^{n - i} b^{i}) = 2^{2} 3^{0} - 2^{1} 3^{1} + 2^{0} 3^{2} = 7
In the second example:
(∑ {i=0}^{n} s{i} a^{n - i} b^{i}) = -1^{4} 5^{0} - 1^{3} 5^{1} - 1^{2} 5^{2} - 1^{1} 5^{3} - 1^{0} 5^{4} = -781 ≡ 999999228 \pmod{10^{9} + 9}.
样例
2 2 3 3
+-+
7
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