uses crt;
var n,i,k:integer;
s,f:real;
begin
clrscr;
write('n=');
readln(n);
s:=0;
f:=1;
k:=-1;
for i:=1 to n do
begin
f:=f/(i+1);
k:=-k;
s:=s+k*f*i;
end;
write('S=',s:0:6);
readln
end.
uses crt;
var n,i,k:integer;
s,f:real;
begin
clrscr;
write('n=');
readln(n);
s:=0;
f:=1;
k:=-1;
for i:=1 to n do
begin
f:=f/(i+1);
k:=-k;
s:=s+k*f*i;
end;
write('S=',s:0:6);
readln
end.