program tallage;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var d,a,y,x,rez1,rez,rez2: array[1..10000] of integer;
    ns,nm,n,i,j,k:integer;
    min,s,c:real;
    f1,f2:text;
begin
assign(f1,'tallage.dat');reset(f1);
assign(f2,'tallage.sol');rewrite(f2);
readln(f1,n);
for i :=1 to n do readln(f1,x[i],y[i]);
//for i :=1 to n+1 do writeln(x[i],' ',y[i]);
//readln;

k:=1;
s:=0;
a[1]:=1;
d[1]:=1;
while k<n do begin
min:=maxint;
for i:=1 to k do
for j:=1 to n do begin
c:=sqrt(sqr(x[d[i]]-x[j])+sqr(y[d[i]]-y[j]));
if (c<=min) and (a[j]=0) And(i<>j) then begin nm:=j;min:=c;ns:=i;
end;
end;
a[nm]:=1;
s:=s+min;
rez1[k]:=ns-1;rez2[k]:=nm-1;

//writeln(k,' ',s:2:2,' ',rez1[k],' ',rez2[k]);
//readln;
k:=k+1;
d[k]:=nm;
end;
writeln(f2,s:3:3);
for i:=1 to n do writeln(f2,rez1[i],' ',rez2[i]);


close(f1);
close(f2);

  { TODO -oUser -cConsole Main : Insert code here }
end.