Compilare: user.cpp: In function ‘bool check(std::string, std::string)’: user.cpp:14:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<=a.length();i++){ ^ user.cpp:15:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=1;j<=b.length();j++){ ^ user.cpp:22:69: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] return (a.length()+b.length()-2*cmlsc[a.length()][b.length()])<=k; ^