function arctg1(x, eps: real; N:integer): real;
var zn,k,s:integer;
    sum,res,xx: real;
begin
    sum:=0;
    s:=1;
      while N>s do
        begin
            if ((s-1)mod 2)=0 then //(-1)^(n-1)
              zn:=1
            else
              zn:=-1;
           xx:=x;
            if s<>1 then
             for k:=1 to 2*s-2 do
               xx:=xx*x;
           res:=zn*xx/(2*s-1);
              if abs(res)>eps then
               sum:=sum+res;
          s:=s+1;
        end;
    arctg1:=sum;
end;

var  x, eps: real;
     i,n: integer;
begin
   write('Vvedite x=');
   readln(x);
   write('Vvedite N=');
   readln(N);
    if (x>-1) and (x<1) and (n>=1) then
     begin
          for i := 1 to 6 do
            begin
               write('Vvedite epsilon=');
               readln(eps);
               writeLn('Znachene cosinusa ravno=', arctg1(x, eps, N):1:8);
            end;
     end
    else
      Write('(x>-1) and (x<1) and (n>=1)');
   readln;
end.