/in/p2.cpp: In function 'opaque_list* insert_list_helper(list_t, list_t, list_t, unsigned int)':
/in/p2.cpp:176:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if(size(first_n_list) == n) return append(reverse(first_n_list), append(second, rest_list));
        ~~~~~~~~~~~~~~~~~~~^~~~
/in/p2.cpp: In function 'opaque_list* chop_helper(list_t, unsigned int, int)':
/in/p2.cpp:195:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if(times == n) return list;
        ~~~~~~^~~~
/tmp/ccuZuhh1.o: In function `main':
main.cpp:(.text+0x533): undefined reference to `tree_sum(opaque_tree*)'
main.cpp:(.text+0x594): undefined reference to `tree_search(opaque_tree*, int)'
main.cpp:(.text+0x5e0): undefined reference to `depth(opaque_tree*)'
main.cpp:(.text+0x629): undefined reference to `tree_max(opaque_tree*)'
main.cpp:(.text+0x672): undefined reference to `traversal(opaque_tree*)'
main.cpp:(.text+0x6c4): undefined reference to `tree_hasMonotonicPath(opaque_tree*)'
main.cpp:(.text+0x728): undefined reference to `tree_allPathSumGreater(opaque_tree*, int)'
main.cpp:(.text+0x78c): undefined reference to `tree_allPathSumGreater(opaque_tree*, int)'
main.cpp:(.text+0x7f2): undefined reference to `covered_by(opaque_tree*, opaque_tree*)'
main.cpp:(.text+0x858): undefined reference to `contained_by(opaque_tree*, opaque_tree*)'
main.cpp:(.text+0x8bc): undefined reference to `insert_tree(int, opaque_tree*)'
collect2: error: ld returned 1 exit status