Compilare: user.cpp: In function ‘void open(int)’: user.cpp:47:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<key[k].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:78:14: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if (a[nx][ny]>0 && stare[nx][ny]!=1) ^