#include <iostream>
#include <vector>
using namespace std;
int countSpecialElements(vector<int>& nums) {
int n = nums.size();
vector<int> dp(n + 1, 0);
for (int i = 0; i < n; ++i) {
for (int j = 0; j < i; ++j) {
if (nums[i] == nums[j] * 3) {
dp[i + 1] = max(dp[i + 1], dp[j + 1] + 1);
}
}
dp[i + 1] = max(dp[i + 1], dp[i]);
}
return dp[n];
}
int main() {
int N;
cin >> N;
vector<int> nums(N);
for (int i = 0; i < N; ++i) {
cin >> nums[i];
}
cout << countSpecialElements(nums) << endl;
return 0;
}
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