#include <iostream>
#include <stack>
#include <vector>
#include <utility>

using namespace std;

struct brace
{
  char c;
  int pos;
};

const vector<pair<char, char>> braces =
  { make_pair('{', '}')
  , make_pair('(', ')')
  , make_pair('<', '>')
  };

int main()
{
  stack<brace> stk;
  char c;
  int pos = 0;
  while (cin.get(c)) {
    ++pos;
    for (const auto &i : braces) {
      if (c == i.first) {
        stk.emplace(brace{ i.second, pos });
      }
      else if (c == i.second) {
        if (stk.empty()) {
          cerr << "Got '" << c << "' bracket without an opening one at "
               << pos << endl;
        } else {
          if (stk.top().c != c) {
            cerr << "Expected '" << stk.top().c << "' bracket (opened at " << stk.top().pos
                 << "), got '" << c << "' instead at " << pos << endl;
          }
          stk.pop();
        }
      }
    }
  }
  while (!stk.empty()) {
    cerr << "Expected '" << stk.top().c << "' bracket (opened at " << stk.top().pos
         << "), got EOF" << endl;
    stk.pop();
  }
  return 0;
}