Chef has two strings A and B consisting of lowercase alphabets, each of length N. Help Chef in finding the number of indices i (1 ≤ i ≤ N) such that $A[i \dots N] < B[i \dots N]$.

$S[i \dots N]$ denotes the suffix of string $S starting at index i, i.e. S_{iS}_{i+1} \dots S_{N}$.
String S < String T denotes that S is lexicographically smaller than T. If two strings S and T have the same length N, we say that S is lexicographically smaller than T if there exists an index i(1 ≤ i ≤ N) such that $S_{1} = T_{1}, S_{2} = T_{2}, \ldots, S_{i-1} = T_{i-1}$ and S_{i} < T_{i}. For example, "abc" is lexicographically smaller than "acd", "abe", but not smaller than "abc", "aac".

------ Input Format ------

• The first line contains T denoting the number of test cases. Then the test cases follow.
• The first line of each test case contains N, denoting the length of the strings A and B.
• The second line of each test case contains the string A.
• The third line of each test case contains the string B.

------ Output Format ------

For each test case, print a single line containing one integer - the number of indices i such that $A[i \dots N] < B[i\dots N]$.

------ Constraints ------

$1 ≤ T ≤ 10^{5}$
$1 ≤ N ≤ 10^{6}$
- The sum of $N$ over all test cases does not exceed $10^{6}$

----- Sample Input 1 ------
2
2
ab
bb
3
aaa
aab
----- Sample Output 1 ------
1
3

----- explanation 1 ------
Test Case $1$:
- For $i = 1$, $A[1 \dots 2] =$ "$ab$", $B[1 \dots 2] =$ "$bb$" and lexicographically, "$ab$" $<$ "$bb$".
- For $i = 2$, $A[2 \dots 2] =$ "$b$", $B[2 \dots 2] =$ "$b$" and lexicographically, "$b$" $=$ "$b$".

Test Case $2$: For each $i \in \{1 , 2, 3\}$, $A[i \dots 3] < B[i \dots 3]$.

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