Given two $n$ by $n$ square matrices $A$ and $B$, write a program to compute the matrix $C = AB$.
Every row of $A$, $B$, and $C$ will be stored sequentially in one file.
All file names for a matrix have the same prefix, and end with its row index start from $1$ to $n$.
For example, if the prefix for $A$ is sample1A, then the first row of $A$ will be stored in a file sample1A1.
All elements in $A$ and $B$ are int32_t, and the elements of $C$ are int64_t.
You should compute $C$ and store it in files.
Input Format (stdin)
The first line is the size of the matrices, $n$.
The second to the fourth lines are the filename prefix for $A$, $B$ and $C$ respectively.
The length of all prefixes are less than 20.
$n \leq 30 $
You should write $C$ into files in the same file name convention as $A$ and $B$, but with type int64_t.