답안

const scores = prompt('점수입력').split(' ').map(function(n){
  return parseInt(n, 10);
});

scores.sort((a, b) => {
  return a-b;
});

let count = 0;
let arr = [];

while (arr.length < 3) {
  let n = scores.pop();
  if (!arr.includes(n)){
    arr.push(n);
  }
  count += 1;
}

console.log(count);