Program Variant_2;
Var s, f, t: Real;
i, n: Word;
Const p=3.14;
Begin
Write('n=');
ReadLn(n);
WriteLn;
WriteLn('----------------');
WriteLn(' i s');
WriteLn('----------------');
t:=1.0;
s:=1.0;
f:=P/4;
For i:=1 To n Do
Begin
t:=-(2*n)/(2*n+1);
s:=s+t;
WriteLn(i:3, ' ', s:0:6);
End;
WriteLn('----------------');
WriteLn;
WriteLn(' f=',f:0:6);
Readln;
End.