/in/foo.cc:10:24: warning: left shift count >= width of type [-Wshift-count-overflow]
 int package[N], f[1 << M];//每一行的二进制数
                        ^
/in/foo.cc: In function 'int h(int)':
/in/foo.cc:19:19: warning: array subscript is above array bounds [-Warray-bounds]
   int i = f[s & -s];
           ~~~~~~~~^
/in/foo.cc: In function 'bool dfs(int, int)':
/in/foo.cc:39:19: warning: array subscript is above array bounds [-Warray-bounds]
   int i = f[s & -s];
           ~~~~~~~~^
/in/foo.cc: In function 'int main()':
/in/foo.cc:54:38: warning: array subscript is above array bounds [-Warray-bounds]
  for (int i = 0; i < n; i++) f[1 << i] = i;
                              ~~~~~~~~^