C++ :: Tail Stiva Crashing To Print?

i am trying to break a string and store it to a stiva (tail) i need my program to take one function like this

(a+10)* ((b+c)/(d-5)) + (9*2)

and return if it is editorial correct for example for the apper function has to return true but for this function

((a+10)*((b+c)/(d-5)) + (9*2)

has to return false.it crashes in the last part of my list i will put a comment

Code: #include<iostream>
#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<string.h>
#include<string>
using namespace std;
struct node{
char info;
node *back;
};

[code]....