program tallage;
{$apptype console}
var a:array[0..100,0..100] of extended;
x,y:array[0..100] of integer;
f1:text;
kol_ver,v:array[0..100] of integer;
n,k,i,j,vi,vj:integer;
min,s:real;
ver:array[0..100,1..2] of integer;
f:boolean;
cc:char;
begin
assign(f1,'tallage.dat');
reset(f1);
read(f1,n);
for i:=0 to n do begin
read(f1,x[i],y[i]);
end;
close(f1);

for i:=0 to n do
for j:=i to n do begin
a[i,j]:=sqrt(sqr(x[i]-x[j])+sqr(y[i]-y[j]));
a[j,i]:=a[i,j];
end;

{for i:=0 to n do begin
for j:=0 to n do
write(a[i,j]:2:2,' ');
writeln;
end;
readln;}




k:=0;
v[k]:=0;
s:=0;
while (k<n) do begin
min:=maxint;
for i:=0 to k do
for j:=0 to n do
if a[v[i],j]<min then begin min:=a[v[i],j];vi:=v[i];vj:=j;end;
f:=true;
for i:=0 to k do if vj=v[i] then f:=false;
if f then
begin
k:=k+1;
ver[k,1]:=vi;
ver[k,2]:=vj;
v[k]:=vj;
kol_ver[vj]:=kol_ver[vj]+1;
kol_ver[vi]:=kol_ver[vi]+1;
s:=s+a[vi,vj];
end;
a[vi,vj]:=1e30;a[vj,vi]:=1e30;


end;
//writeln(s:3:3);readln;
assign(f1,'tallage.sol');
rewrite(f1);
writeln(f1,s:3:3);
for i:=1 to n do
writeln(f1,ver[i,1],' ',ver[i,2]);
close(f1);

end.