typedef long unsigned int L;
typedef void rw(L);
void gen (rw rep, int n){L t = 0;
void rg(int p, int m){
// rg's job is to put m ones in the right p bits of t and call rep for each.
// Then leave t as it was.
if(m) {int j=p; L x = t; while(j--) {t |= 1l<<j; rg(j, m-1); t = x;}} else rep(t);}
{int l; for(l = 0; l<=n; ++l) rg(n, l);}}

#include <stdio.h>
int w = 0;
void Rep(L o) {printf("%4lx\n", o); ++w;}
int main(){gen(Rep, 14); printf("w=%d\n", w);
  return 0;}