Compilare: user.cpp: In function ‘bool bellmanford()’: user.cpp:67:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0;i < G[node].size();i++) ^ user.cpp: In function ‘void read(int&)’: user.cpp:36:42: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buff,1,Mn,stdin),pos = 0; ^ user.cpp:44:42: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buff,1,Mn,stdin),pos = 0; ^ user.cpp: In function ‘bool bellmanford()’: user.cpp:88:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:92:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bellmanford.in","r",stdin); ^ user.cpp:93:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bellmanford.out","w",stdout); ^