Find correct assignment statements. Part $3$

Cost: $16|$ Solved: $1$

Memory limit: $256$ Mb

Time limit: $1000$ ms

Input file: stdin

Output file: stdout

Task:

You are given a set of strings separated with line feed characters.

Find all the substrings that are correct assignment statements.

The general formula for a valid assignment statement is $$x $=$ y;$,$ where x is the first operand, y is the second operand. Note that there may be several whitespace characters between the operands.

In this task a string is considered to be a correct assignment statement when:

$1)$ a variable is assigned to a constant value;

$2)$ a variable is assigned to another variable;

$3)$ a variable is assigned to an arithmetic expression;

$4)$ a variable is assigned to an array element which index is either a numeric value, a variable or an arithmetic expression.

For example, the strings $"$a$3$a$=7$;$","$a $=$ b;$","$a$[$i$]=$b$[$j$]$;$","$a$=$z$[2]$;$","$a$=$f$*2$;$","$a$[5]=$z$+$a;$","$a $=$ z$[$i$+7]$;$","$a $=$ z$[$i$+7]+11$;$"$ are considered to be correct assignment statements $($note that there is a semicolon at the end of each statement$).$

The strings $"$a$=6","$a$-=10$;$","$a$+=$n;$","$d$=$#$&$\_$h$","$a$*=$r;$"$ are considered to be incorrect.

Input:

A set of strings separated with line feed characters.

Output:

All the longest correct substrings in the order in which they appear in the text, separating each with a line feed character.

$**$ Use only C$++**$