Compilare: user.cpp: In function ‘int main()’: user.cpp:36:64: warning: iteration 10u invokes undefined behavior [-Waggressive-loop-optimizations] for(int i=4;i<=30;++i) dp[i]=5LL*dp[i-1]-5LL*dp[i-2]+dp[i-3]; ^ user.cpp:36:5: note: containing loop for(int i=4;i<=30;++i) dp[i]=5LL*dp[i-1]-5LL*dp[i-2]+dp[i-3]; ^