C reworked

#define _CRT_SECURE_NO_DEPRECATE

#include <iostream>
#include <vector>
#include <string>
#include <map>
#include <stack>

using namespace std;


int main() {
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
	string s;
	cin >> s;
	stack<char> c;
	for (int i = 0; i < s.size(); i++) {
		if (s[i] == ')') {
			if (c.size() == 0) {
				printf("at position %d : expected ( or END, found )", i + 1);
				return 0;
			}
			if (c.top() == '|') {
				c.pop();
				c.pop();
			}
			else {
				printf("at position %d : expected ( or |, found (", i + 1);
				return 0;
			}
		}
		if (s[i] == '|') {
			if (c.size() == 0) {
				printf("at position %d : expected (, found |", i + 1);
				return 0;
			}
			if (c.top() == '|') {
				printf("at position %d : expected ( or ), found |", i + 1);
				return 0;
			}
			c.push('|');
		}
		if (s[i] == '(') {
			c.push('(');
		}
	}
	if (c.size() == 0) {
		cout << "correct, length = " << s.size();
		return 0;
	}
	if (c.size() != 0) {
		if (c.top() == '(') {
			printf("at position %d: expected ( or |, found END", s.size() + 1);
			return 0;
		}
		else {
			printf("at position %d: expected ( or ), found END", s.size() + 1);
			return 0;
		}
	}
}