Compilare: user.cpp: In function ‘void rec(int, int, int, int)’: user.cpp:24:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i<s.size()&&x1<=x2&&y1<=y2) ^ user.cpp:23:9: warning: variable ‘nr’ set but not used [-Wunused-but-set-variable] int nr,k,q,a,b,c,d,e,f; ^ user.cpp: In function ‘int main()’: user.cpp:71:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<s.size();i++) ^