import java.io.*;
import java.util.*;
public class Main{
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
while(sc.hasNextLine()){
int n = Integer.parseInt(sc.nextLine());
int[][] num = new int[n][n];
for(int i = 0; i < n; ++i){
String[] ss = sc.nextLine().split(",");
for(int j = 0; j < ss.length; ++j){
num[i][j] = Integer.parseInt(ss[j]);
}
}
int[][] dp = new int[n][n];
for(int i = 0; i < n; ++i){
for(int j = 0; j < n; ++j){
if(i == 0 && j == 0){
dp[i][j] = num[i][j];
}else if(i == 0){
dp[i][j] = dp[i][j - 1] + num[i][j];
}else if(j == 0){
dp[i][j] = dp[i - 1][j] + num[i][j];
}else{
dp[i][j] = Math.min(dp[i - 1][j],dp[i][j - 1]) + num[i][j];
}
}
}
System.out.println(dp[n - 1][n - 1]);
}
}
}