Compilare: user.cpp: In function ‘int main()’: user.cpp:14:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); ++i)a[i + 1] = s[i]; ^ user.cpp:16:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); ++i)b[i + 1] = s[i]; ^ user.cpp:19:34: warning: left operand of comma operator has no effect [-Wunused-value] for(int i = st, j = m; i >= 1, j >= 1;) ^