/in/foo.cc: In function 'int main()':
/in/foo.cc:101:9: warning: unused variable 'nonsense' [-Wunused-variable]
     int nonsense = dfs2(d_start, 0, 1);
         ^~~~~~~~
/in/foo.cc: In function 'int dfs2(int, int, int)':
/in/foo.cc:63:24: warning: 'len' may be used uninitialized in this function [-Wmaybe-uninitialized]
         d[num][1] = len-dis;
                     ~~~^~~~