Compilare: user.cpp: In function ‘int main()’: user.cpp:63:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0;k<p[j].size();++k) ^ user.cpp:65:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0;k<p[i].size();++k) ^ user.cpp:67:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0;k<p[i].size();++k) ^