/AIRCON - Điều hòa không khí

              Uses Crt;
        Var  n,i,left,right,count:longint; a,b:array[1..1000] of longint;
        Procedure Hoanvi(var a,b:longint); var tg:longint; begin tg:=a; a:=b; b:=tg; end;
        Procedure Sort(l,r:longint);
        var i,j,x:longint;
        begin
            i:=l;
            j:=r;
            x:=b[(l+r) div 2];
            repeat
                while b[i]<x do inc(i); while b[j]>x do dec(j);
                if i<=j then
                begin
                    Hoanvi(a[i],a[j]); Hoanvi(b[i],b[j]); inc(i); dec(j);
                end;
            until i>j;
            if j>l then sort(l,j);
            if i<r then sort(i,r);
        end;
        Begin
            readln(n);
            for i:=1 to n do
             begin
                readln(a[i],b[i]);
             end;
            Sort(1,n);
            right:=b[1];
            //for i:=1 to n do writeln(a[i],' ',b[i]);
            count:=1;
            for i:=2 to n do
            begin
                if a[i]>right then
                   begin
                       right:=b[i];
                       inc(count);
                   end;
            end;
            writeln(count);
            readln;
        End.