function solve(name, area, population, country, postCode)
{
    let city =
    {
        name: name,
        area: area,
        population: population,
        country: country,
        postCode: postCode
    };
    let output = '';
    for(let key in city)
    {
        output += `${key} -> ${city[key]}\n`;
    }
    return output;
}

console.log(solve("Sofia"," 492", "1238438", "Bulgaria", "1000"));