

function Main(input) {
  input = input.split("\n");
  var N = parseInt(input[0].split(" ")[0]);
  var A = parseInt(input[0].split(" ")[1]);
  var B = parseInt(input[0].split(" ")[2]);
  var C = parseInt(input[0].split(" ")[3]);
  var mod=Math.pow(10,9)+7;
  var ans=0;
  for(var i=N;i<=2*N-1;i++){
    ans+=combination(i-1,N-1)*(Math.pow(A/100,N)*Math.pow(B/100,i-N)+Math.pow(A/100,i-N)*Math.pow(B/100,N))*i*(100/(100-C));
  }
  var memo={};
  function combination(n, k){
    //メモるまでもなく出る値はそのまま返す
    if(k*2 > n) k=n-k;
    if(k===0) return 1;
    if(k===1) return n;
    //メモを確認
    var memo_key = n + ',' + k;
    if(!memo[memo_key]){
      memo[memo_key] = combination(n-1, k) + combination(n-1, k-1);
    }
    return memo[memo_key];
  }

  console.log('%s', ans);
  return ans;
}

function debug(n){
  var input = document.getElementById("input"+n).value;
  var ans=Main(input);
  var result="WA";
  if(ans==document.getElementById("output"+n).value.split("\n")[0]){
    result="AC";
  }
  document.getElementById("result"+n).innerHTML=result;
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));