A. Even Substringstime limit per test0.5 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputYou are given a string s=s_1s_2\dots s_n of length n, which only contains digits 1, 2, ..., 9.A substring s[l \dots r] of s is a string s_l s_{l + 1} s_{l + 2} \ldots s_r. A substring s[l \dots r] of s is called even if the number represented by it is even. Find the number of even substrings of s. Note, that even if some substrings are equal as strings, but have different l and r, they are counted as different substrings.InputThe first line contains an integer n (1 \le n \le 65000) — the length of the string s.The second line contains a string s of length n. The string s consists only of digits 1, 2, ..., 9.OutputPrint the number of even substrings of s.ExamplesInput
4
1234
Output
6Input
4
2244
Output
10NoteIn the first example, the [l, r] pairs corresponding to even substrings are:   s[1 \dots 2] s[2 \dots 2] s[1 \dots 4] s[2 \dots 4] s[3 \dots 4] s[4 \dots 4] In the second example, all 10 substrings of s are even substrings. Note, that while substrings s[1 \dots 1] and s[2 \dots 2] both define the substring "2", they are still counted as different substrings.
4
1234

6
['implementation', 'strings', '*800']