Compilare: user.cpp: In function ‘int main()’: user.cpp:80:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int k = 0; k < P.size(); k++ ) ^ user.cpp:84:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int k = 0; k < P.size(); k++ ){ ^ user.cpp:101:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < P.size(); i++ ){ ^