Compilare: user.cpp: In function ‘int main()’: user.cpp:102:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < vX.size() - 1 ; ++ j) ^ user.cpp:107:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = vX.size() - 1 ; j < vY.size() ; ++ j) ^ user.cpp:115:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < vY.size(); ++ j) ^ user.cpp:123:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = vY.size() + 1 ; j < vX.size() ; ++ j) ^