Compilare: user.cpp: In function ‘void Manacher()’: user.cpp:20:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size(); i++) ~~^~~~~~~~~~ user.cpp:25:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < b.size(); i++) ~~^~~~~~~~~~ user.cpp:28:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i + k < b.size() && i - k >= 0 && b[i + k] == b[i - k]) ~~~~~~^~~~~~~~~~ user.cpp: At global scope: user.cpp:36:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^ user.cpp: In function ‘int main()’: user.cpp:41:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < b. size(); i++) ~~^~~~~~~~~~~