import java.util.*;

public class Main {
    static final int N = 110;
    static int[][] f = new int[N][N];
    static int n;

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        n = Integer.parseInt(sc.nextLine());

        for (int i = 1; i <= n; i++)
            for (int j = 1; j <= n; j++)
                f[i][j] = sc.nextInt();
        int ans = dp();
        System.out.println(ans);
    }

    static int dp() {
        for (int i = 1; i <= n; i++) 
            for (int j = 1; j <= n; j++)
                if (i == 1) f[i][j] += f[i][j - 1];
                else if (j == 1) f[i][j] += f[i - 1][j];
                else f[i][j] += Math.min(f[i - 1][j], f[i][j - 1]);

        return f[n][n];
    }
}