program book(input,output);
var
 f1,f2:array[0..400,0..400]of longint;
 i,j,k:longint;
 n:longint;
 a:Array[1..400]of longint;

function min(a,b:longint):longint;
begin
 if a>b then min:=b else min:=a;
end;

begin
 assign(input,'book.in');
 reset(input);
 readln(n);
 for i:=1 to n do
 begin
  readln(k,j);
  a[i]:=abs(k-j);
 end;
 close(input);

 for i:=1 to n do
  for j:=1 to n do
   f1[i,j]:=999999;

 for i:=1 to n do
 begin
  f1[i,i]:=0;
  f2[i,i]:=a[i];
 end;

 for k:=1 to n do
  for i:=1 to n-k+1 do
   for j:=i to i+k-1 do
    if f1[i,i+k-1]>f1[i,j]+f1[j+1,i+k-1]+f2[i,j]+f2[j+1,i+k-1] then
    begin
     f1[i,i+k-1]:=f1[i,j]+f1[j+1,i+k-1]+f2[i,j]+f2[j+1,i+k-1];
     f2[i,i+k-1]:=f2[i,j]+f2[j+1,i+k-1];
    end;

 assign(output,'book.out');
 rewrite(output);
 writeln(f1[1,n]);
 close(output);
end.