function solve(arr) {


let companies = {};

let arr2 = [];



  for (let el of arr) {

    let cur = el.split(' -> ');


    if (companies.hasOwnProperty(cur[0])) {

    companies[cur[0]].push(cur[1]);

    } else {

      companies[cur[0]] = [cur[1]];

    }


  }


    for (let key in companies) {

      arr2.push([key, companies[key]]);

    }

    // console.log(arr2);


    arr2.sort((a, b) => a[0].localeCompare(b[0]));


  for (let el of arr2) {

    el[1] = [...new Set(el[1])];


    console.log(el[0]);

    for (let el2 of el[1]) {

      console.log(`-- ${el2}`);

    }



  }




}