//先求出层数
int dfs1(int count,int sum,int step)
{
  if(sum>=count)
  { 
    cout<<"step="<<step<<endl;
    return 1;
  }
  sum+=pow(2,step);
  dfs1(count,sum,step+1);
  return step;
}

int main()
{
  int sum=1;
  dfs1(1, sum,1);
  return 0;
}