Compilare: user.cpp:26:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^ user.cpp: In function ‘int main()’: user.cpp:43:5: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(grad[i]) ^ user.cpp:81:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ans.size() - 1; i++) ~~^~~~~~~~~~~~~~~~