Vasya plays the LionAge II. He was bored of playing with a stupid computer, so he installed this popular MMORPG, to fight with his friends. Vasya came up with the name of his character — non-empty string s , consisting of a lowercase Latin letters. However, in order not to put up a front of friends, Vasya has decided to change no more than k letters of the character name so that the new name sounded as good as possible. Euphony of the line is defined as follows: for each pair of adjacent letters x and y ( x immediately precedes y ) the bonus c(x, y) is added to the result. Your task is to determine what the greatest Euphony can be obtained by changing at most k letters in the name of the Vasya's character.

输入描述:

The first line contains character's name s and an integer number k (0 ≤ k ≤ 100). The length of the nonempty string s does not exceed 100. The second line contains an integer number n (0 ≤ n ≤ 676) — amount of pairs of letters, giving bonus to the euphony. The next n lines contain description of these pairs «xyc», which means that sequence xy gives bonus c (x, y — lowercase Latin letters, - 1000 ≤ c ≤ 1000). It is guaranteed that no pair xy mentioned twice in the input data.

输出描述:

Output the only number — maximum possible euphony оf the new character's name.

备注:

In the first example the most euphony name will be looser. It is easy to calculate that its euphony is 36.