B'You are given two strings s , t of length n , m , respectively. Both strings consist of lowercase letters of the English alphabet. Count the triples (x, y, z) of strings such that the following conditions are true: The first line contains two integers n and m ( 1 <= q n < m <= q 10^7 ) -- the length of the strings s and t , respectively. The second line contains the string s of length n , consisting of lowercase letters of the English alphabet. The third line contains the string t of length m , consisting of lowercase letters of the English alphabet. Output a single integer: the number of valid triples (x, y, z) . In the first test case, the only valid triple is (x, y, z) = ( texttt{"a"}, texttt{"bc"}, texttt{"d"}) . In fact, In the second test case, there are 5 valid triples: In the third test case, there are 8 valid triples: '...