import java.util.LinkedList;
import java.util.PriorityQueue;
import java.util.Scanner;
public class Main {
static int garo;
static int sero;
static int arr[][];
static PriorityQueuepq;
static int result;
static int realdepth;
static int dx[] = {-1,0,1,0};
static int dy[] = {0,1,0,-1};
static int visit[][];
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
garo = sc.nextInt();
sero = sc.nextInt();
pq = new PriorityQueue();
sc.nextLine();
arr= new int[sero][garo];
visit= new int[sero][garo];
for(int i=0;i<sero;i++) {
String s= sc.nextLine();
for(int j=0;j<garo;j++) {
arr[i][j]=s.charAt(j)-'0';
}
}
for(int i=0;i<sero;i++) {
for(int j=0;j<garo;j++) {
visit[i][j]=Integer.MAX_VALUE;
}
}
pq.add(new pos(0,0,0));
visit[0][0]=0;
BFS();
System.out.println(result);
//출력
}
public static void BFS() {
while(!pq.isEmpty()) {
pos temp = pq.poll();
int x = temp.x;
int y = temp.y;
int count= temp.count;
if(x==sero-1&&y==garo-1) {
result = count;
return;
}
for(int i=0;i<4;i++) {
int rx = x+dx[i];
int ry = y+dy[i];
if(rx<0||ry<0||rx>=sero||ry>=garo) {
continue;
}
if(visit[rx][ry]>visit[x][y]+arr[rx][ry]) {
visit[rx][ry] = visit[x][y]+arr[rx][ry];
pq.add(new pos(rx,ry,visit[rx][ry]));
}
}
}
}
private static class pos implements Comparable{
int x;
int y;
int count;
pos(int x, int y, int count){
this.x=x;
this.y=y;
this.count=count;
}
public int compareTo(pos o) {
return this.count
