#include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for (int i=0;i<(n);i++)
#define REP2(i,m,n) for (int i=m;i<(n);i++)
typedef long long ll;
typedef long double ld;

unordered_map<int, double> trans[1<<14];
double dp[2][1<<14];

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    const int T = 14;
    int N;
    double P[3];
    cin >> N;
    REP(i, 3) cin >> P[i], P[i] /= 100.0;

    for (int m1 = 0; m1 < (1 << T); ++m1) {
        for(int m2 = m1; m2 >= 0; --m2) {
            m2 &= m1;
            double tmp = 1;
            for (int i = 0; i < T; ++i) {
                if ((1 << i) & m1) {
                    bool l = (i != 0) && ((1 << (i-1)) & m1);
                    bool r = (i != T-1) && ((1 << (i+1)) & m1);
                    double safe;
                    if (l && r)
                        safe = 1 - P[2];
                    else if (l || r)
                        safe = 1 - P[1];
                    else
                        safe = 1 - P[0];
                    tmp *=  ((1 << i) & m2) ? safe : 1 - safe;
                }
            }
            trans[m1][m2] = tmp;
        }
    }

    REP(i, 2) REP(j, 1<<T) dp[i][j] = 0;
    dp[0][(1<<T)-1] = 1;
    int cur = 0, tar = 1;

    REP(i, 80-N) {
        REP(j, 1<<T)
            dp[tar][j] = 0;
        REP(m1, 1<<T) {
            if (dp[cur][m1] == 0)
                continue;
            for (auto itr: trans[m1])
                dp[tar][itr.first] += dp[cur][m1] * itr.second;
        }
        swap(cur, tar);
    }

    double ans = 0;
    REP(mask, 1<<T)
        ans += dp[cur][mask] * __builtin_popcount(mask);
    cout.precision(20);
    cout << fixed  << ans*2 << endl;
}