Compilare: user.cpp: In function ‘int main()’: user.cpp:47:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (k[0] < v[0].size() && k[1] < v[1].size() && k[0] + k[1] < n) { ^ user.cpp:47:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (k[0] < v[0].size() && k[1] < v[1].size() && k[0] + k[1] < n) { ^ user.cpp:57:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (k[0] < v[0].size()) { ^ user.cpp:61:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (k[1] < v[1].size()) { ^