Rectangle

Rectangle

const
  max=100;
  fin='rectangle.in';
  fout='rectangle.out';
var
  f:array[0..max+1,0..max+1] of integer;
  n,k,i,j,x1,y1,x2,y2,ans:integer;
begin
  assign(input,fin); reset(input);
  assign(output,fout);rewrite(output);
  fillchar(f,sizeof(f),0);
  readln(n);
  for k:=1 to n do
    begin
      readln(x1,y1,x2,y2);
      for i:=x1+1 to x2 do
        for j:=y1+1 to y2 do f[i,j]:=1;
    end;
  ans:=0;
  for i:=0 to max+1 do
    for j:=0 to max+1 do inc(ans,f[i,j]);
  writeln(ans);
  close(input);close(output);
end.