{ Tianjiao Zhang Phillips Academy Senior Division }

Var sets,n,r,b,w,nu,de:longint;

s:string; ch:char; rep:boolean;

Procedure

get(c:char);

begin case c of 'R':begin nu:=nu*r; if not rep then dec(r) end;

'B':begin nu:=nu*b;

if not rep then dec(b) end;

'W':begin nu:=nu*w; if not rep

then dec(w) end;

'r':nu:=nu*(n-r);

'b':nu:=nu*(n-b);

'w':nu:=nu*(n-w); else exit

end;

de:=de*n;

if not rep then dec(n) end;

Begin {

assign(input,'PROB.in');

reset(input);} sets:=5;

while sets>0 do begin dec(sets);

read(n,r,b,w);

n:=r+b+w;

de:=1;nu:=1;

read(ch);

while ch=' ' do read(ch);

if not((ch='Y')or(ch='N')) then get(ch) else begin if ch='Y' then rep:=true else

rep:=false; readln(s);

while s<>'' do begin get(s[1]);

delete(s,1,1) end end;

writeln(nu,'/',de) end;

close(input) End.