AKs Special String

AK is provided with two strings, $A$ and $B$. But he likes the string only if a certain property is satisfied by the string. The certain property is given as:- If there are two strings $A$ and $B$ and $A_i$ and $B_i$ denotes the ith character of the string $A$ and $B$ respectively. The property satisfies if :- $B_{1} - A_{1} =…….....= B_{i-1} - A_{i-1} = B_i - A_i = B_{i+1} - A_{i + 1} = ……