This program about { convert infix to postfix } . I want any notes, if any

#include<iostream>
#include<stack>
#include<string>
#include<vector>
using namespace std;
int Priority(char symbol)
{                                        // to found priority of the symboles
	if (symbol == '(')
		return 3;
	else
		if (symbol == '/' || symbol == '*')
			return 2;
		else
			if (symbol == '+' || symbol == '-')
				return 1;
}
bool IsOperation(char symbol)                   // return true if symbole ,else return false {like numbers}
{
	return (symbol == '(' || symbol == '/' || symbol == '*' || symbol == '+' || symbol == '-');
}

bool IsNumber(char symble)               // return true if numbers , else return false {like operation + - ...}
{
	return (symble == '0' || symble == '1' || symble == '2' || symble == '3' || symble == '4' || symble == '5' || symble == '6'

		|| symble == '7' || symble == '8' || symble == '9');
}

void main()                            // start Function main
{
	stack<char>postfix;
	stack<char>OPERATION;
	string x;
	cout << "Enter your process without spaces to convert infix to postfix : ";
	cin >> x;   // enter x
	
	
	for (int i = 0; i < x.size(); i++)  // To Check on every index in x string
		
	{
		if (x[i] == ')')                                               // This's case if the symbole { ) } it means the end of the brackets { (..) }
		{                                                             // and this will insert  all element in operation stack	                                                         
			while (OPERATION.top() != '('&& !OPERATION.empty())      //to postfix stack and remove all element into { ( } in operation stack
			{                                                       // then remove the symbole{ ( }
				postfix.push(OPERATION.top());
				OPERATION.pop();
			}
			OPERATION.pop();
		}
		
		else	
			if (IsNumber(x[i]))                   // if symoble is Number enter to stack "  postfix "
		{
			if (IsOperation(x[i+1]))       // To check if i need to put space or not
			{
				postfix.push(x[i]);
				postfix.push(' ');
			}
			else
			{
				postfix.push(x[i]);
			}
		}
		else                                 // else if symoble is operation
			if (IsOperation(x[i]))
			{
				if (OPERATION.empty())
				{
					OPERATION.push(x[i]);
				}
				else
					if (Priority(x[i]) > Priority(OPERATION.top()) || OPERATION.top() == '(')  // insert in stack operation if element of index is operation or 
						                                                                    //  OPERATION.top()=='('
					{
						OPERATION.push(x[i]);
					}
				else
				{
					while ((!OPERATION.empty())&& Priority(OPERATION.top()) >= Priority(x[i]) )     // Repetition the body of while into 
						                                                                   // stack operation become empty and Priority OPERATION.top()   
					{
						if (OPERATION.top() == '(')
						{
							break;
						}                                                            // and Priority(OPERATION.top()) >= Priority(x[i])
						postfix.push(OPERATION.top());                                     // then insert to operation stack x[i]
						OPERATION.pop();
					}
					OPERATION.push(x[i]);
				}
			}
			else                        // This's case if the symbole is not operation and number // in fact the enter is error
			{
				cout << "Go out" << endl;
				break;
			}
	}                 // finish for loop

	while (!OPERATION.empty())                      // insert all element in operation stack to postfix stack and remove all element in operation stack
	{                                               // because we have finished converting
		postfix.push(OPERATION.top());
		OPERATION.pop();
	}


	vector<char> q;
	 
	while (!postfix.empty())
	{
		q.push_back(postfix.top());
		postfix.pop();
	}
	cout << endl;
	cout << "Before the conversion process : " << x << endl;
	cout << "After the conversion process : ";

	for (int i = q.size() - 1; i >= 0; --i)
	{
		cout << q[i] ;
	}


	cout << endl;
	system("pause");
}