Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:55:31: 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:85:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < V[i].size(); ++ j) ^ user.cpp: In function ‘void read()’: user.cpp:38:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("obiective.in", "r", stdin); ^ user.cpp:39:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:43:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^ user.cpp: In function ‘void write()’: user.cpp:133:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("obiective.out", "w", stdout); ^ user.cpp:134:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &q); ^ user.cpp:138:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^