Compilare: user.cpp: In function ‘void biconex(int, int)’: user.cpp:20:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0 ; i<a[x].size() ; ++i) ^ user.cpp: In function ‘int main()’: user.cpp:66:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0 ; i<sol.size() ; ++i) ^ user.cpp:68:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0 ; j<sol[i].size() ; ++j) ^