package graph;

import java.util.*;

public class algospot {

public static int n, m;

public static int map[][];

public static int visited[][];

static int[] dx = {0,1,0,-1};

static int[] dy = {1,0,-1,0};

static int result = 0;

static class Spot implements Comparable<Spot>{

int x;

int y;

int cnt;

public Spot(int x, int y, int cnt) {

this.x = x;

this.y = y;

this.cnt = cnt;

}

@Override

public int compareTo(Spot o) {

// TODO Auto-generated method stub

return this.cnt < o.cnt ? -1 : 1;

}

}

public static void bfs() {

PriorityQueue<Spot> q = new PriorityQueue<Spot>();

q.add(new Spot(0,0,0));

visited[0][0] = 0;

while(!q.isEmpty()) {

Spot spot = q.poll();

if(spot.x==n-1 && spot.y==m-1) {

result = spot.cnt;

return;

}

for(int i=0;i<4;i++) {

int nx = spot.x+dx[i];

int ny = spot.y+dy[i];

if(nx<0||ny<0||nx>=n||ny>=m)continue;

if(visited[nx][ny]>visited[spot.x][spot.y]+map[nx][ny]) {

visited[nx][ny] = visited[spot.x][spot.y]+map[nx][ny];

q.add(new Spot(nx,ny,visited[nx][ny]));

}

}

}

}

public static void main(String[] args) {

//#1261¹ø_¾Ë°í½ºÆÌ

Scanner sc = new Scanner(System.in);

m = sc.nextInt();

n = sc.nextInt();

map = new int[n][m];

visited = new int[n][m];

for(int i=0; i<n; i++) {

for(int j=0; j<m; j++) {

visited[i][j] = Integer.MAX_VALUE;

}

}

for(int i=0; i<n; i++) {

String input = sc.next();

for(int j=0; j<m; j++) {

map[i][j] = input.charAt(j)-'0';

}

}

bfs();

System.out.println(result);

}

}