function test() {
  var input = '1 + 2\n56 - 18\n13 * 2\n100 / 10\n27 + 81\n0 ? 0'.split('\n');
  return input.map(function(x) {
    var calc = {
      '+': function(a, b) {return a + b;},
      '-': function(a, b) {return a - b;},
      '*': function(a, b) {return a * b;},
      '/': function(a, b) {return ~~(a / b);},
      '?': function(a, b) {return;}
    };
    var arr = x.split(' ');
    return (Number(arr[0]) + Number(arr[2]));
  }).join('\n').trim();
}