program one;
const k=9;
Var a,n:integer;
s:real;
begin
a:=1;
s:=0;
For n:=1 to k do
a:=a*(-1);
s:=s+a/n;
n:=n+2;
writeln('s= ',s:4:4);
readln;
End.
program one;
const k=9;
Var a,n:integer;
s:real;
begin
a:=1;
s:=0;
For n:=1 to k do
a:=a*(-1);
s:=s+a/n;
n:=n+2;
writeln('s= ',s:4:4);
readln;
End.