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

auto rdsp(){return readln.splitter;}
void pick(R,T)(ref R r,ref T t){t=r.front.to!T;r.popFront;}
void readV(T...)(ref T t){auto r=rdsp;foreach(ref v;t)pick(r,v);}
void readS(T)(size_t n,ref T t){t=new T(n);foreach(ref v;t){auto r=rdsp;foreach(ref j;v.tupleof)pick(r,j);}}

void main()
{
  int n, m; readV(n, m);
  struct R { int a, b; }
  R[] r; readS(m, r);

  r.sort!"a.b<b.b";

  auto x = 0, s = 0;
  foreach (ri; r)
    if (ri.a > x) {
      ++s;
      x = ri.b-1;
    }

  writeln(s);
}
