Compilare: user.cpp: In function ‘void DFS(int, int)’: user.cpp:23:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < G[n].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:55:11: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] else if (c == ans.c) ^ user.cpp:29:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("concurs.in", "r", stdin); ^ user.cpp:30:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("concurs.out", "w", stdout); ^ user.cpp:32:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &M); ^ user.cpp:33:50: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (int i = 1; i <= N; ++i) scanf("%d", &pr[i]); ^ user.cpp:36:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] G[x].push_back(y); ^ user.cpp:47:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n1, &n2); ^