Compilare: user.cpp: In function ‘void dfs(long long int)’: user.cpp:20:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i<v[nod].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:33:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hektor.in","r",stdin); ^ user.cpp:35:51: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld %lld %lld %lld\n", &n, &m ,&a, &b); ^ user.cpp:37:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld", &cost[i]); ^ user.cpp:42:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld %lld", &x, &y); ^