#include<bits/stdc++.h>
using namespace std;
int a,b,c,d;
double dp[20][20][20][20][5][5];
double ans;
double dfs(int ax,int bx,int cx,int dx,int joker1,int joker2) {
    if(dp[ax][bx][cx][dx][joker1][joker2]>=1e-8) return dp[ax][bx][cx][dx][joker1][joker2];
    int tot=ax+bx+cx+dx+(joker1!=0)+(joker2!=0);
    if(ax+(joker1==1)+(joker2==1)>=a&&
       bx+(joker1==2)+(joker2==2)>=b&&
       cx+(joker1==3)+(joker2==3)>=c&&
       dx+(joker1==4)+(joker2==4)>=d) {
        return 0;
    }
    dp[ax][bx][cx][dx][joker1][joker2]=1.0;
    if(ax<13)
        dp[ax][bx][cx][dx][joker1][joker2]+=dfs(ax+1,bx,cx,dx,joker1,joker2)*(13-ax)/(54-tot);
    if(bx<13)
        dp[ax][bx][cx][dx][joker1][joker2]+=dfs(ax,bx+1,cx,dx,joker1,joker2)*(13-bx)/(54-tot);
    if(cx<13)
        dp[ax][bx][cx][dx][joker1][joker2]+=dfs(ax,bx,cx+1,dx,joker1,joker2)*(13-cx)/(54-tot);
    if(dx<13)
        dp[ax][bx][cx][dx][joker1][joker2]+=dfs(ax,bx,cx,dx+1,joker1,joker2)*(13-dx)/(54-tot);
    if(!joker1) {
        double minn=999999999;
        minn=min(minn,dfs(ax,bx,cx,dx,4,joker2)/(54-tot));
        minn=min(minn,dfs(ax,bx,cx,dx,3,joker2)/(54-tot));
        minn=min(minn,dfs(ax,bx,cx,dx,2,joker2)/(54-tot));
        minn=min(minn,dfs(ax,bx,cx,dx,1,joker2)/(54-tot));
        dp[ax][bx][cx][dx][joker1][joker2]+=minn;
    }
    if(!joker2) {
        double minn=999999999;
        minn=min(minn,dfs(ax,bx,cx,dx,joker1,4)/(54-tot));
        minn=min(minn,dfs(ax,bx,cx,dx,joker1,3)/(54-tot));
        minn=min(minn,dfs(ax,bx,cx,dx,joker1,2)/(54-tot));
        minn=min(minn,dfs(ax,bx,cx,dx,joker1,1)/(54-tot));
        dp[ax][bx][cx][dx][joker1][joker2]+=minn;
    }
    return dp[ax][bx][cx][dx][joker1][joker2];
}
int main() {
    cin>>a>>b>>c>>d;
    int joker=2;
    if(a>13) {
        joker-=a-13;
    }
    if(b>13) {
        joker-=b-13;
    }
    if(c>13) {
        joker-=c-13;
    }
    if(d>13) {
        joker-=d-13;
    }
    if(joker<0) {
        printf("-1.000");
        return 0;
    }
    ans=dfs(0,0,0,0,0,0);
    printf("%.3lf",ans);
    return 0;
}