Compilare: user.cpp: In function ‘void bellman_ford()’: user.cpp:33:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<a[x].size();j++) ^ user.cpp: In function ‘int main()’: user.cpp:48:17: warning: unused variable ‘x’ [-Wunused-variable] int i,j,k,l,x; ^ user.cpp:46:27: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(inf,"r",stdin); ^ user.cpp:47:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(outf,"w",stdout); ^ user.cpp:49:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:52:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d",&i,&j,&k); ^