Compilare: user.cpp: In function ‘void make_graph()’: user.cpp:54:26: warning: statement has no effect [-Wunused-value] gr[i*n+ii]; ^ user.cpp: In function ‘void toposort(int)’: user.cpp:98:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();i++) ^ user.cpp: In function ‘bool con(int, int)’: user.cpp:123:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[a].size();i++) ^