Compilare: user.cpp: In function ‘void bellman_ford()’: user.cpp:13:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<al[x].size();++i) ^ user.cpp:22:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<al[u].size();++j) ^ user.cpp: In function ‘int main()’: user.cpp:97:34: 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:98:36: 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:100:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&n,&m,&U,&x); ^ user.cpp:101:44: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int u=1;u<=U;++u) scanf("%d",&t[u]); ^ user.cpp:104:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&i,&j); ^