program book(input,output);
 
var
  n,i,j,k,min,x,y:longint;
  g,f:array[0..400,0..400]of longint;
 
begin
  assign(input,'book.in');
  reset(input);
 
  assign(output,'book.out');
  rewrite(output);
 
  readln(n);
 
  for i:=1 to n do
  begin
    read(x,y);
    g[i,i]:=x-y;
    g[1,i]:=g[1,i-1]+g[i,i];
  end;
 
  for i:=2 to n do
    for j:=i+1 to n do
      g[i,j]:=g[i,j-1]+g[j,j];
 
  for i:=1 to n-1 do
    for j:=1 to n-i do
    begin
      x:=j;
      y:=i+j;
 
      min:=f[x,y-1];
 
      for k:=x+1 to y-1 do
        if f[x,k-1]+f[k,y]<min then
          min:=f[x,k-1]+f[k,y];
 
      if f[x+1,y]<min then
        min:=f[x+1,y];
 
      f[x,y]:=min+g[x,y];
    end;
 
  writeln(f[1,n]);
 
  close(input);
  close(output);
end.