B'You are given a string s=s_1s_2 ... s_n of length n , which only contains digits 1 , 2 , ..., 9 . A substring s[l ... r] of s is a string s_l s_{l + 1} s_{l + 2} ldots s_r . A substring s[l ... 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. The first line contains an integer n ( 1 <= n <= 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 . Print the number of even substrings of s . In the first example, the [l, r] pairs corresponding to even substrings are: In the second example, all 10 substrings of s are even substrings. Note, that while substrings s[1 ... 1] and s[2 ... 2] both define the substring "2", they are still counted as different substrings. '...