Compilare: user.cpp: In function ‘void df(int)’: user.cpp:23:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] fr(j,0,out[i].size()){ ^ user.cpp:3:33: note: in definition of macro ‘fr’ #define fr(i,a,b) for(int i=a;i<b;++i) ^ user.cpp: In function ‘int main()’: user.cpp:53:12: warning: ‘a2’ may be used uninitialized in this function [-Wmaybe-uninitialized] int a1,a2,a3; ^