import std.algorithm, std.container, std.conv, std.math, std.range, std.typecons, std.stdio, std.string;

void readV(T...)(ref T t){auto r=readln.splitter;foreach(ref v;t){v=r.front.to!(typeof(v));r.popFront;}}
void readC(T...)(size_t n,ref T t){foreach(ref v;t)v=new typeof(v)(n);foreach(i;0..n){auto r=readln.splitter;foreach(ref v;t){v[i]=r.front.to!(ElementType!(typeof(v)));r.popFront;}}}

void main()
{
  int n; readV(n);
  int[] l, r; readC(n, l, r);

  auto t = 0;
  foreach (li, ri; lockstep(l, r))
    t += ri-li+1;
  writeln(t);
}
