Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:17:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a[u].size();++i){ ^ user.cpp:25:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<node.size();++i) res.push_back(iii(d[node[i]],ii(U,node[i]))); ^ user.cpp: In function ‘int main()’: user.cpp:46:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a[s].size();++i){ ^ user.cpp:57:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<res.size();++i) { ^ user.cpp:31:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("atac2.in","r",stdin); ^ user.cpp:32:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("atac2.out","w",stdout); ^ user.cpp:34:31: 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,&s); ^ user.cpp:37:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^ user.cpp:42:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&p,&q); ^