One Swap String Conversion

Given two strings s and t, determine whether it is possible to convert s into t by performing at most one swap operation on s. In one swap operation, you can choose two distinct indices i and j (with i ≠ j) and exchange s[i] and s[j].

Note that:

• If s is already equal to t, the answer is YES.
• The lengths of s and t must be equal. Otherwise, the answer is NO.
• If there are exactly two indices i and j where s and t differ, then the conversion is possible if and only if swapping these two positions in s results in t; mathematically, this can be represented as: $$ s[i] = t[j] \quad \text{and} \quad s[j] = t[i] $$.

Otherwise, the answer is NO.

inputFormat

The input is read from standard input and has the following format:

T
s₁ t₁
s₂ t₂
... 
sₜ tₜ

where T (an integer) is the number of test cases, and for each test case there are two strings s and t separated by whitespace.

outputFormat

For each test case, print a single line with YES if s can be converted into t with at most one swap operation, and NO otherwise.

1
a a

YES