test

let countrys ={
    Bulgaria: {
        Sofia:{
          population: 1242000
        },
        Plovdiv:{
          population: 669796
        }
    },
    Macedonia: {
        Skopje:{
          population: 627498
        },
        Ohrid:{
            population: 42000
        }

    }
}

let sorted = Object.keys(countrys).sort((a,b)=>
    getPop(countrys[b],'population') - getPop(countrys[a],'population') || a.localeCompare(b))

sorted.forEach(element=>{
    console.log(`country: ${element}`);
    let town = countrys[element];
    let sort = Object.keys(town).sort((a,b)=>
       town[a].population - town[b].population
    )
    sort.forEach(el=>{
        console.log(`town: ${el} - population: ${town[el].population}`);
    })
    console.log('-'.repeat(50))
})

function getPop(country,type){
    let minNum = Number.MAX_SAFE_INTEGER;

    Object.keys(country).forEach(el=>{
        let minPopulation = country[el][type];// ili countrys

        if(minNum > minPopulation){
            minNum = minPopulation;
        }
    });
    return minNum;
}