Compilare: user.cpp: In function ‘int main()’: user.cpp:21:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<s.size()-1;++i) ^ user.cpp:22:17: warning: suggest parentheses around comparison in operand of ‘!=’ [-Wparentheses] if (s[i]<s[i+1]!=s[i-1]<s[i]) ^ user.cpp:32:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<s.size();++i) ^ user.cpp:50:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<st.size();++i) ^