Compilare: main.cpp: In function 'void topo(int)': main.cpp:18:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<graph[nod].size();++i) ~^~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:28:28: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&n,&m); ^ main.cpp:32:32: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&x,&y); ^