uses crt;
var n,i,f,a,b:integer;
s,t:real;
begin
clrscr;
repeat
write('Введите n>1 n=');
readln(n);
until n>1;
s:=0;
t:=1;
a:=1;
b:=1;
for i:=1 to n do
begin
if odd(i) then
begin
f:=a+b;
a:=b;
b:=f;
end;
t:=t/(2*i-1);
s:=s+f*t;
end;
write('S=',s:0:4);
readln
end.