#include<bits/stdc++.h>
#define ll long long
#define M 501
using namespace std;
ll n;
ll a[M],dp[M][M];
int main(){
	cin>>n;
	for(ll i=1;i<=n;i++)
		cin>>a[i];
	for(ll l=1;l<=n;l++)
		for(ll i=1;i+l-1<=n;i++){
			ll j=i+l-1;
			if(i==j) dp[i][j]=1;
			else if(i+1==j) dp[i][j]=1+(a[i]!=a[j]);
			else if(a[i]==a[j]) dp[i][j]=dp[i+1][j-1];
			else{
				dp[i][j]=INT_MAX;
				for(ll k=i;k<j;k++)
					dp[i][j]=min(dp[i][j],dp[i][k]+dp[k+1][j]);
			}
			//cout<<i<<' '<<j<<' '<<dp[i][j]<<endl;
		}
	cout<<dp[1][n];
	return 0;
}
/*
7
1 4 4 2 3 2 1

*/