c = (program, register, undefined) => {
  // These variable declarations are just to aid compression and should be removed from the compressed output
  var memory, instruction_pointer, memory_pointer, write_char, level, commands, instruction, tokens, instructions, find_matching, memory_value;

  memory = [instruction_pointer = memory_pointer = 0];
  write_char = output_char;

  find_matching = (start, stop, direction) => {
    level = 1;
    instruction_pointer += direction;
    while(level += instructions[instruction_pointer += direction] == start ? 1 : instructions[instruction_pointer] == stop ? -1 : 0);
  }

  commands = {
    moo: $ => find_matching(tokens[0], tokens[7], -1) | instruction_pointer--,
    mOo: $ => memory_pointer--,
    moO: $ => memory[++memory_pointer] |= 0,
    mOO: $ => memory_value == 3 || commands[tokens[memory_value]](),
    Moo: $ => memory_value ? write_char(String.fromCharCode(memory_value)) : memory[memory_pointer] = input_char(),
    MOo: $ => memory[memory_pointer]--,
    MoO: $ => memory[memory_pointer]++,
    MOO: $ => memory_value || find_matching(tokens[7], tokens[0], 1),
    OOO: $ => memory[memory_pointer] = 0,
    MMM: $ => register ? (memory[memory_pointer] = register, register = undefined) : register = memory_value,
    OOM: $ => [...memory_value+''].map(write_char)
  };

  tokens = Object.keys(commands);
  instructions = program.match(RegExp(tokens.join`|`, 'g'));

  while (instruction = instructions[instruction_pointer]) {
    commands[instruction](memory_value = memory[memory_pointer]);
    instruction_pointer++;
  }
};