C. Levko and Stringstime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputLevko loves strings of length n, consisting of lowercase English letters, very much. He has one such string s. For each string t of length n, Levko defines its beauty relative to s as the number of pairs of indexes i, j (1 ≤ i ≤ j ≤ n), such that substring t[i..j] is lexicographically larger than substring s[i..j].The boy wondered how many strings t are there, such that their beauty relative to s equals exactly k. Help him, find the remainder after division this number by 1000000007 (109 + 7).A substring s[i..j] of string s = s1s2... sn is string sisi  +  1... sj.String x  =  x1x2... xp is lexicographically larger than string y  =  y1y2... yp, if there is such number r (r < p), that x1  =  y1,  x2  =  y2,  ... ,  xr  =  yr and xr  +  1 > yr  +  1. The string characters are compared by their ASCII codes.InputThe first line contains two integers n and k (1 ≤ n ≤ 2000, 0 ≤ k ≤ 2000).The second line contains a non-empty string s of length n. String s consists only of lowercase English letters. OutputPrint a single number — the answer to the problem modulo 1000000007 (109 + 7).ExamplesInput2 2yzOutput26Input2 3yxOutput2Input4 7abcdOutput21962
Input2 2yz
Output26
['combinatorics', 'dp', '*2500']