Compilare: user.cpp: In function ‘void spirala(int, int, std::vector<std::vector<int> >)’: user.cpp:40:27: warning: unused variable ‘s’ [-Wunused-variable] int m1=0,n1=0,k,d=1,l,s; ^ user.cpp:41:10: warning: unused variable ‘b’ [-Wunused-variable] bool b=true; ^ user.cpp: At global scope: user.cpp:104:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^ user.cpp: In function ‘void spirala(int, int, std::vector<std::vector<int> >)’: user.cpp:101:9: warning: ‘l’ may be used uninitialized in this function [-Wmaybe-uninitialized] o<<l; ^