/* FILE: collage.cpp   last change: 20-Sept-2012   author: Romeo Rizzi
 * a solver for problem "collage" in the 28-Sept-2012 exam in Algorithms.
 */

#define NDEBUG // NDEBUG disabilita tutte le assert se definita prima di includere <cassert> 
#include <cassert>

#ifndef NDEBUG
#  include <iostream>  // non voglio includerla quando Non compilo in modalita' DEBUG 
#endif

#include <fstream>

using namespace std;

const int MAX_N = 1000; int n;
int color[MAX_N];

int memo[MAX_N +1][MAX_N +1];

int main (int argc, char** argv) {
	ifstream in("input.txt"); assert( in );
	in >> n;
      	for(int i = 0; i < n; ++i)  in >> color[i];
	in.close();
	
	for(int i = n-1; i >= 0; --i)
	   for(int j = 0; j < n; ++j)
	       if( i>j ) memo[i][j] = 0;
	       else {
		   memo[i][j] = 1 + memo[i+1][j];
		   for(int sec = 1; i + sec <= j; ++sec)
		       if( color[i+sec] == color[i] )
			 memo[i][j] = min(memo[i][j], memo[i+1][i+sec-1] + memo[i+sec][j]);
	       }
	
	ofstream out("output.txt"); assert( out );
	out << memo[0][n-1] << endl;
	out.close();

	return 0;
}