Compilare: main.cpp: In function 'void compute_levels(int, int)': main.cpp:36:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<arcs[node].size(); ++i) { ~^~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:76:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("lca.in", "r", stdin); ^ main.cpp:77:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("lca.out", "w", stdout); ^ main.cpp:80:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:88:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^ main.cpp:97:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^