program factorial;
function fac (n:integer):longint;
var
i:integer;
rez:longint;
begin
rez:=1;
for i:=1 to n do
rez:=rez*i;
fac:=rez;
end;
var
n,m:integer;
begin
read(n,m);
writeln((fac(n)+fac(m))/(fac(n+m)):0:7);
end.
Вариант 2
uses crt;
var m,n:integer;
l:real;
function fac(n:integer):longint;
begin
if (n=0) or (n=1) then fac:=1 else fc:=n*f(n-1);
end;
begin
clrscr;
write('N,M -> ');
readln(n,m);
l:=(fac(m)+fac(n))/fac(n+m);
write('L=',l:0:4);
readln;
end.