Compilare: user.cpp: In function ‘int main()’: user.cpp:30:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[0].size(); i++) { ^ user.cpp:34:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(;k<v[j].size() && v[j][k] < v[0][i]; k++); ^ user.cpp:35:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( k==v[j].size() || v[j][k]>v[0][i] ) { ^ user.cpp:48:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<res.size(); i++) ^