Compilare: main.cpp: In function 'void dfs(int)': main.cpp:24:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0 ; i < G[u].size() ; i ++) ~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:54:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("petrica.in" , "r" , stdin); ^ main.cpp:55:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("petrica.out" , "w" , stdout); ^ main.cpp:57:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &n); ^ main.cpp:59:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &p[i]); ^ main.cpp:62:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d" , &x , &y); ^