Compilare: user.cpp: In function ‘int main()’: user.cpp:44:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<A[col].size();++i) ^ user.cpp:55:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<A[col].size();++i) ^ user.cpp:67:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<R[lin].size();++i) ^