Const
 Nmax=100;

Var
 x,y:Array[1..Nmax] of Real;
 i,N:Byte;
 a,b,S_x,S_y,S_x2,S_xy:Real;

Begin
 Write('N= ');
 Readln(N);
 S_x:=0;
 S_y:=0;
 S_x2:=0;
 S_xy:=0;
 for i:=1 to N do
  begin
   write('x[',i,']= ');
   readln(x[i]);
   write('y[',i,']= ');
   readln(y[i]);
   S_x:=S_x+x[i];
   S_y:=S_y+y[i];
   S_x2:=S_x2+Sqr(x[i]);
   S_xy:=S_xy+x[i]*y[i];
  end;
 writeln;
 a:=(S_x2*S_y-S_x*S_xy)/(N*S_x2-Sqr(S_x));
 b:=(N*S_xy-S_x*S_y)/(N*S_x2-Sqr(S_x));
 writeln('a= ',a:0:5);
 writeln('b= ',b:0:5);
 writeln;
 writeln('     x              y            a+bx');
 for i:=1 to N do
  writeln(x[i]:8:3,y[i]:15:3,(a+b*x[i]):15:3);
 readln
End.