#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
#include <stack>
#include <string>

bool bracketsMatch(std::istream &in) {
    std::stack<char> expectedDelimiters;
    int lineNum = 0;
    std::string line;
    while (std::getline(in, line)) {
        lineNum++;
        size_t pos = 0;
        while (std::string::npos != (pos = line.find_first_of("(){}[]", pos))) {
            int colNum = pos + 1;
            switch (line[pos]) {
              case '(': expectedDelimiters.push(')'); break;
              case '{': expectedDelimiters.push('}'); break;
              case '[': expectedDelimiters.push(']'); break;

              case ']':
              case '}':
              case ')':
                if (expectedDelimiters.empty()) {
                    std::cout << "Mismatched " << line[pos]
                              << " at line " << lineNum << ", col " << colNum
                              << std::endl;
                    return false;
                }
                if (line[pos] != expectedDelimiters.top()) {
                    std::cout << "Expected " << expectedDelimiters.top()
                              << ", found " << line[pos]
                              << " at line " << lineNum << ", col " << colNum
                              << std::endl;
                    return false;
                }
                expectedDelimiters.pop();
            }
            pos = colNum;
        }
    }
    // Should check for a possible input error here, but I didn't bother.
    if (!expectedDelimiters.empty()) {
        std::cout << "Expected " << expectedDelimiters.top()
                  << " at end of file" << std::endl;
        return false;
    }
    return true;
}

int main(int argc, const char *argv[]) {
    // The command-line parsing below is a bit sloppy (no validation,
    // help message, or option handling, for example).
    std::ifstream f;
    std::istream &in = (argc > 1) ? (f.open(argv[1]), f) : std::cin;
    if (!in) {
        std::cerr << argv[0] << ": " << argv[1] << ": "
                  << std::strerror(errno) << std::endl;
        return 2;   // A rather arbitrary error code
    }
    return bracketsMatch(in) ? EXIT_SUCCESS : EXIT_FAILURE;
}