program stergeri;
var f,g:text;
    min,v:array[1..100000]of longint;
    a,b,n,m,k,y,c,t,ok,i:longint;
begin
assign(f,'stergeri.in');
assign(g,'stergeri.out');
reset(f);
rewrite(g);
read(f,n,m,k);
c:=k;
t:=0;
for y:=1 to m do
  begin
    read(f,a,b);
    ok:=0;
    for i:=1 to t do
      begin
        if (min[i]>a)then
          begin
            ok:=1;
            break;
          end;
      end;
    if (ok=1)then
      begin
        min[i]:=a;
        v[i]:=v[i]+(b-a+1);
      end else
      begin
        t:=t+1;
        min[t]:=a;
        v[t]:=b-a+1;
      end;
  end;
for i:=1 to t do
  begin
    if (min[i]<=k)then c:=c+v[i];
  end;
write(g,c);
close(f);
close(g);
end.