#include <cstdio>
#include <array>
#define repeat(i,n) for (int i = 0; (i) < int(n); ++(i))
using namespace std;
const int K = 14;
int main() {
    int a; scanf("%d", &a);
    double p[3]; repeat (i,3) { scanf("%lf", &p[i]); p[i] /= 100; }
    array<double, (1<<K)> dp = {};
    dp[(1<<K) - 1] = 1;
    for (; a < 80; ++ a) {
        repeat (s, 1<<K) {
            double q = 0;
            for (int t = s; t < (1<<K); ++ t |= s) { // s \subseteq t
                double r = dp[t];
                for (int i = 1; i <= (1<<K); i <<= 1) if (t & i) {
                    int j = bool(t & (i>>1)) + bool(t & (i<<1));
                    r *= (s & i ? 1 - p[j] : p[j]);
                }
                q += r;
            }
            dp[s] = q;
        }
    }
    double acc = 0;
    repeat (s, 1<<K) acc += __builtin_popcount(s) * dp[s];
    printf("%.10lf\n", acc * 2);
    return 0;
}