Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:13:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < V[x].size(); ++ i) ^ user.cpp: In function ‘void solve()’: user.cpp:51:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < V[nod].size(); ++ j) ^ user.cpp: In function ‘void read()’: user.cpp:23:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("marvel.in", "r", stdin); ^ user.cpp:24:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d", &n, &m, &k, &p); ^ user.cpp:26:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^ user.cpp:28:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &e[i]); ^ user.cpp:32:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^ user.cpp: In function ‘void write()’: user.cpp:59:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("marvel.out", "w", stdout); ^