Compilare: main.cpp: In function 'void df(int)': main.cpp:17:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<a[k].size(); i++) ~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:43:11: warning: unused variable 'j' [-Wunused-variable] int i,j,x,y; ^ main.cpp:44:27: 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:47:31: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d",&x,&y); ^