Compilare: main.cpp: In function 'void DFS(int, int)': main.cpp:20:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<g[semn][u].size(); j++) ~^~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:51:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in", "r", stdin); ^ main.cpp:52:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out", "w", stdout); ^ main.cpp:54:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:57:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &u, &v); ^