Compilare: user.cpp: In function ‘int main()’: user.cpp:53:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<p[i].size(); ++j) ^ user.cpp:15:28: warning: ‘x2’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (!a || !b) return a+b; ^ user.cpp:46:12: note: ‘x2’ was declared here int x1,x2; ^ user.cpp:15:28: warning: ‘x1’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (!a || !b) return a+b; ^ user.cpp:46:9: note: ‘x1’ was declared here int x1,x2; ^