#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=2e9+1;
const ll INF=4e18;
const ll dy[8]={-1,0,1,0,1,1,-1,-1};
const ll dx[8]={0,-1,0,1,1,-1,1,-1};
template <typename T> inline bool chmax(T &a, T b) {
  return ((a < b) ? (a = b, true) : (false));
}
template <typename T> inline bool chmin(T &a, T b) {
  return ((a > b) ? (a = b, true) : (false));
}
using ld=long double;
vector<ld> p(3);
ld memo[25][15][2];
ld dp(ll y,ll v,ll left){
  if(v==0)return 0;
  if(y==0)return v;
  if(memo[y][v][left]!=-1)return memo[y][v][left];
  ld ans=0;
  ld prob=1;//自分より左の歯が残る確率
  rep(i,v){
    ld nowp;//i番目の歯が抜ける確率
    if(i==0&&left&&v==1)nowp=p[0];
    else if(i==0&&left)nowp=p[1];
    else if(i==v-1)nowp=p[1];
    else nowp=p[2];
    ans+=prob*nowp*(dp(y-1,i,1)+dp(y,v-i-1,0));
    prob*=(ld)1.0-nowp;
  }
  ans+=prob*dp(y-1,v,1);
  memo[y][v][left]=ans;
  return ans;
}
int main(){
  ll n;cin >> n;n=80-n;
  rep(i,3)cin >> p[i];rep(i,3)p[i]/=100;
  rep(i,25)rep(j,15)rep(k,2)memo[i][j][k]=-1;
  CST(10);
  cout << dp(n,14,1)*2 << endl;
}