JaeHyeonKim19

import java.io.*;
import java.util.*;

public class Main {
	static int [][] nums;
	static boolean [][] isCombined;
	static int answer;

	static void resetIsCombined () {
		for(int i = 0; i < isCombined.length; i++) {
			for(int j = 0; j < isCombined[i].length; j++) {
				isCombined[i][j] = false;
			}
		}
	}

	static int getMaxValue (int [][] nums) {
		int max = 0;
		for(int i = 0; i < nums.length; i++) {
			for(int j = 0; j < nums[i].length; j++) {
				max = nums[i][j] > max ? nums[i][j] : max;
			}
		}
		return max;
	}

	static void move (int [][] priorNums, int dir, int count) {
		if(count == 5) {
			int curMaxVal = getMaxValue(priorNums);
			if(curMaxVal > answer) answer = curMaxVal;
			return;
		}
		int [][] curNums = new int[priorNums.length][priorNums.length];
		for(int i = 0; i < priorNums.length; i++) {
			for(int j = 0; j < priorNums[i].length; j++) {
				curNums[i][j] = priorNums[i][j];
			}
		}
		if(dir == 0) {
			for(int i = 0; i < curNums.length; i++) {
				for(int j = 0; j < curNums.length; j++) {
					if(curNums[j][i] != 0) {
						for(int k = 0; k < j; k++) {
							if(curNums[k][i] != 0) {
								if(!isCombined[k][i] && curNums[k][i] == curNums[j][i] && (curNums[k+1][i] == 0 || k + 1 == j)) {
									curNums[k][i] *= 2;
									isCombined[k][i] = true;
									curNums[j][i] = 0;
									break;
								}
							} else {
								curNums[k][i] = curNums[j][i];
								curNums[j][i] = 0;
								break;
							}
						}
					}
				}
			}
		}else if(dir == 1) {
			for(int i = 0; i < curNums.length; i++) {
				for(int j = curNums.length - 1; j >= 0; j--) {
					if(curNums[j][i] != 0) {
						for(int k = curNums.length - 1; k > j; k--) {
							if(curNums[k][i] != 0) {
								if(!isCombined[k][i] && curNums[k][i] == curNums[j][i] && (curNums[k-1][i] == 0 || k - 1 == j)) {
									curNums[k][i] *= 2;
									isCombined[k][i] = true;
									curNums[j][i] = 0;
									break;
								}
							} else {
								curNums[k][i] = curNums[j][i];
								curNums[j][i] = 0;
								break;
							}
						}
					}
				}
			}
		}else if(dir == 2) {
			for(int i = 0; i < curNums.length; i++) {
				for(int j = 0; j < curNums.length; j++) {
					if(curNums[i][j] != 0) {
						for(int k = 0; k < j; k++) {
							if(curNums[i][k] != 0) {
								if(!isCombined[i][k] && curNums[i][k] == curNums[i][j] && (curNums[i][k+1] == 0 || k + 1 == j)) {
									curNums[i][k] *= 2;
									isCombined[i][k] = true;
									curNums[i][j] = 0;
									break;
								}
							} else {
								curNums[i][k] = curNums[i][j];
								curNums[i][j] = 0;
								break;
							}
						}
					}
				}
			}
		}else if(dir == 3) {
			for(int i = 0; i < curNums.length; i++) {
				for(int j = curNums.length - 1; j >= 0; j--) {
					if(curNums[i][j] != 0) {
						for(int k = curNums.length - 1; k > j; k--) {
							if(curNums[i][k] != 0) {
								if(!isCombined[i][k] && curNums[i][k] == curNums[i][j] && (curNums[i][k-1] == 0 || k - 1 == j)) {
									curNums[i][k] *= 2;
									isCombined[i][k] = true;
									curNums[i][j] = 0;
									break;
								}
							} else {
								curNums[i][k] = curNums[i][j];
								curNums[i][j] = 0;
								break;
							}
						}
					}
				}
			}
		}
		resetIsCombined();
		move(curNums, 0, count + 1);
		move(curNums, 1, count + 1);
		move(curNums, 2, count + 1);
		move(curNums, 3, count + 1);
	}

	public static void main(String[] args) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		nums = new int[n][n];
		isCombined = new boolean[n][n];
		answer = 0;
		StringTokenizer st;
		for(int i = 0; i < n; i++) {
			st = new StringTokenizer(br.readLine());
			for(int j = 0; j < n; j++) {
				nums[i][j] = Integer.parseInt(st.nextToken());
			}
		}
		move(nums, 0, 0);
		move(nums, 1, 0);
		move(nums, 2, 0);
		move(nums, 3, 0);
		System.out.print(answer);
	}
}