H, W = map(int, input().split())
A = [input() for _ in range(H)]

l = [[0] * W for i in range(H)]

l[0][0]=1
l[H-1][W-1]=1
aa=0
ab=0
ba=H-1
bb=W-1
a=0
b=0
c=1
cnt=2
while (c>=1):
    m=0
    if(a%2==0):
        if(aa>0 and l[aa-1][ab]==0):
            if(m==0 or A[aa-1][ab]<m):
                m=A[aa-1][ab]
                a=aa-1
                b=ab
                
        if(ab>0 and l[aa][ab-1]==0):
            if(m==0 or A[aa][ab-1]<m):
                m=A[aa][ab-1]
                a=aa
                b=ab-1
                
        if(aa<W and l[aa+1][ab]==0):
            if(m==0 or A[aa+1][ab]<m):
                m=A[aa+1][ab]
                a=aa+1
                b=ab
                
        if(ab<H and l[aa][ab+1]==0):
            if(m==0 or A[aa][ab+1]<m):
                m=A[aa][ab+1]
                a=aa
                b=ab+1
        
        l[a][b]=1
        aa=a
        bb=b
        if(a>0):
            if(l[a-1][b]==2):
                break
        if(b>0):
            if(l[a][b-1]==2):
                break
        if(a<H-1):
            if(l[a+1][b]==2):
                berak
        if(b<W-1):
            if(l[a][b+1]==2):
                berak
        cnt+=1    
    else:
        if(ba>0 and l[ba-1][bb]==0):
            if(m==0 or A[ba-1][bb]<m):
                m=A[ba-1][bb]
                a=ba-1
                b=bb
                
        if(bb>0 and l[ba][bb-1]==0):
            if(m==0 or A[ba][bb-1]<m):
                m=A[ba][bb-1]
                a=ba
                b=bb-1
                
        if(bb>W and l[ba+1][bb]==0):
            if(m==0 or A[ba+1][bb]<m):
                m=A[ba+1][bb]
                a=ba+1
                b=bb
        
        if(bb>H and l[ba][bb+1]==0):
            if(m==0 or A[ba][bb+1]<m):
                m=A[ba][bb+1]
                a=ba
                b=bb+1
        
        l[a][b]=2
        aa=a
        bb=b
        
        if(a>0):
            if(l[a-1][b]==1):
                break
        if(b>0):
            if(l[a][b-1]==1):
                break
        if(a<H-1):
            if(l[a+1][b]==1):
                break
        if(b<W-1):
            if(l[a][b+1]==1):
                break
        
        cnt+=1

print(cnt)