text: function solve(params) {
      let towns = {};
  
      for (const line of params) {
          let [town, population] = line.split(' <-> ');
          if (!towns[town]) {
              towns[town] = 0;
          }
  
          towns[town] += +population;
      }
  
      Object
          .entries(towns)
          .forEach(([town, population]) => {
              console.log(`${town} : ${population}`);
          });
  }
  
  solve([
      'Sofia <-> 1200000',
      'Montana <-> 20000',
      'New York <-> 10000000',
      'Washington <-> 2345000',
      'Las Vegas <-> 1000000'
  ]);