Compilare: user.cpp: In function ‘ll back(unsigned int)’: user.cpp:10:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<L;i++) { ^ user.cpp:14:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(max(a,b) != -1 && (max(a,b)+C[i] < D[st] || D[st] == 0)) D[st] = max(a,b)+C[i]; ^ user.cpp: In function ‘int main()’: user.cpp:23:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<N;i++){ ^ user.cpp:25:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0;j<L;j++){cin>>c; A[j]+=(c == '1' ? (1<<i) : 0);} ^ user.cpp:27:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0;j<L;j++) cin >> C[j]; ^