Compilare: user.cpp: In function ‘void euler()’: user.cpp:59:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1;i<=n;i++) eul[i]=i; ^ user.cpp:60:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=2;i<=n;i++) { ^ user.cpp:61:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (eul[i]==i) for (j=i;j<=n;j+=i) eul[j] /=i, eul[j] *= (i-1); ^ user.cpp: In function ‘int main()’: user.cpp:74:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=2;i<=n;i++) fr += eul[i]; ^