Compilare: user.c: In function ‘kfib’: user.c:49:5: warning: operation on ‘nr’ may be undefined [-Wsequence-point] v[++nr] = matmult(v[nr - 1], v[nr - 1]); ^ user.c:49:5: warning: operation on ‘nr’ may be undefined [-Wsequence-point] user.c: In function ‘main’: user.c:17:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("kfib.in", "r", stdin); ^ user.c:18:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("kfib.out", "w", stdout); ^ user.c:19:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld", &k); ^