Compilare: user.cpp: In function ‘void preg(int, int)’: user.cpp:29:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < g[x].size(); ++i) ^ user.cpp: In function ‘void solve(int, int)’: user.cpp:45:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < g[x].size(); ++i) ^ user.cpp:51:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < d.size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:72:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("invtree.in", "r", stdin); ^ user.cpp:73:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("invtree.out", "w", stdout); ^ user.cpp:75:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &k); ^ user.cpp:78:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &x, &y, &l); aux.l = l; ^