Compilare: main.cpp: In function 'void dfs1(Pal*)': main.cpp:67:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<nnod->v.size(); i++){ ~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:82:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] { freopen("pal2.in", "r", stdin); ^ main.cpp:83:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pal2.out", "w", stdout); ^ main.cpp:85:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s", s); ^