Compilare: user.cpp:9:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^ user.cpp: In function ‘int main()’: user.cpp:13:55: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j,k=s.size()+1,i=s.size()-1; i>=s.size()/2; i--) ^ user.cpp:18:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (; k>=0 && j<y.size(); k--,j++) ^ user.cpp:20:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j==y.size()) x=i; ^ user.cpp:23:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s[q]!=s[x+1] && x+1<s.size()) q++; ^