Compilare: main.cpp: In function 'void dfs1(int, int)': main.cpp:15:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < G[u].size() ; j ++) ~~^~~~~~~~~~~~~ main.cpp: In function 'void dfs2(int, int)': main.cpp:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < T[u].size() ; j ++) ~~^~~~~~~~~~~~~ main.cpp: In function 'void get_int(int&)': main.cpp:31:39: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buffer , sz , 1 , stdin); ^ main.cpp:39:39: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buffer , sz , 1 , stdin); ^ main.cpp: In function 'int main()': main.cpp:46:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("cerere.in" , "r" , stdin); ^ main.cpp:47:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("cerere.out" , "w" , stdout); ^