Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:33:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<G[node].size(); ++i) { ^ user.cpp: In function ‘bool bellmanford()’: user.cpp:58:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<BG[node].size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:103:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0; j<G[center].size(); ++j) { ^ user.cpp:86:36: 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:87:38: 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:91:46: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &n, &m, &army, &center); ^ user.cpp:94:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^ user.cpp:97:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^