03. Population in Towns

function solve(arr) {
  const mapWithTowns = new Map();

  arr.forEach((el) => {
    const [town, population] = el.split(/\s+<->\s+/);

    if (!mapWithTowns.has(town)) {
      mapWithTowns.set(town, 0);
    }

    mapWithTowns.set(town, mapWithTowns.get(town) + Number(population));
  });

  mapWithTowns.forEach((value, key) => {
    console.log(`${key} : ${value}`);
  });
}