Compilare: main.cpp: In function 'void dfs(int)': main.cpp:18:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<g[u].size(); i++) ~^~~~~~~~~~~~ main.cpp: In function 'void DFS(int, int)': main.cpp:29:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<g[u].size() && !viz[w]; i++) ~^~~~~~~~~~~~ main.cpp:35:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<r[u].size() && !viz[w]; i++) ~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:47:40: 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); ^ main.cpp:48:42: 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); ^ main.cpp:50:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:53:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &u, &v); ^ main.cpp:57:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ main.cpp:60:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &u, &v); ^