Compilare: user.cpp: In function ‘void DF(int, int)’: user.cpp:35:13: warning: unused variable ‘a’ [-Wunused-variable] int y=0,a,b; ^ user.cpp:35:15: warning: unused variable ‘b’ [-Wunused-variable] int y=0,a,b; ^ user.cpp: In function ‘void Write_Data()’: user.cpp:97:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<sol.size();++i) ^ user.cpp:100:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<sol[i].size();++j) ^