Compilare: user.cpp: In function ‘int main()’: user.cpp:30:48: warning: suggest parentheses around ‘-’ inside ‘<<’ [-Wparentheses] else c[s2[0]-'A'][s2[1]-'A']|=(1<<s1[0]-'A'); ^ user.cpp:36:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size();++i) ^ user.cpp:37:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<s.size();++j)lit[i][j]=viz[i][j]=0; ^