#include <bits/stdc++.h>
                                        #include<iostream>
                                        #include<cstdio>
                                        #include<vector>
                                        #include<queue>
                                        #include<map>
                                        #include<cstring>
                                        #include<string>
                                        #include <math.h>
                                        #include<algorithm>
                                    //    #include <boost/multiprecision/cpp_int.hpp>
                                        #include<functional>
                        //       #define int long long
                                        #define inf  1000000007
                                        #define pa pair<int,int>
                                        #define ll long long
                                        #define pal pair<double,double>
                                        #define ppap pair<pa,int>
                                  
                                        #define ssa pair<string,int>
                                        #define  mp make_pair
                                        #define  pb push_back
                                        #define EPS (1e-7)
                                        #define equals(a,b) (fabs((a)-(b))<EPS)
int dx[4]={0,-1,0,1};
int dy[4]={1,0,-1,0};
                                        using namespace std;
                               			class pa3{
                                        	public:
                                        	int x,y,z;
                                        	pa3(int x=0,int y=0,int z=0):x(x),y(y),z(z) {}
                                        	bool operator < (const pa3 &p) const{
                                        		if(x!=p.x) return x<p.x;
                                        		if(y!=p.y) return y<p.y;
                                        		 return z<p.z;
                                        		//return x != p.x ? x<p.x: y<p.y;
                                        	}
                               				bool operator > (const pa3 &p) const{
                                        		if(x!=p.x) return x>p.x;
                                        		if(y!=p.y) return y>p.y;
                                        		 return z>p.z;
                                        		//return x != p.x ? x<p.x: y<p.y;
                                        	}
                                        	bool operator == (const pa3 &p) const{
                                        		return x==p.x && y==p.y && z==p.z;
                                        	}
                                        		bool operator != (const pa3 &p) const{
                                        			return !( x==p.x && y==p.y && z==p.z);
                                        	}
                                        
                                        };
                                        
                                        class pa4{
                                        	public:
                                        	int x;
                                        	int y,z,w;
                                        	pa4(int x=0,int y=0,int z=0,int w=0):x(x),y(y),z(z),w(w) {}
                                        	bool operator < (const pa4 &p) const{
                                        		if(x!=p.x) return x<p.x;
                                        		if(y!=p.y) return y<p.y;
                                        		if(z!=p.z)return z<p.z;
                                        		return w<p.w;
                                        		//return x != p.x ? x<p.x: y<p.y;
                                        	}
                                        	bool operator > (const pa4 &p) const{
                                        		if(x!=p.x) return x>p.x;
                                        		if(y!=p.y) return y>p.y;
                                        		if(z!=p.z)return z>p.z;
                                        		return w>p.w;
                                        		//return x != p.x ? x<p.x: y<p.y;
                                        	}
                                        	bool operator == (const pa4 &p) const{
                                        		return x==p.x && y==p.y && z==p.z &&w==p.w;
                                        	}
                                        		
                                        
                                        };
                                        class pa2{
                                        	public:
                                        	int x,y;
                                        	pa2(int x=0,int y=0):x(x),y(y) {}
                                        	pa2 operator + (pa2 p) {return pa2(x+p.x,y+p.y);}
                                        	pa2 operator - (pa2 p) {return pa2(x-p.x,y-p.y);}
                                        	bool operator < (const pa2 &p) const{
                                        		return x != p.x ? x<p.x: y<p.y;
                                        	}
                                        	bool operator > (const pa2 &p) const{
                                        		return x != p.x ? x>p.x: y>p.y;
                                        	}
                                        	bool operator == (const pa2 &p) const{
                                        		return abs(x-p.x)==0 && abs(y-p.y)==0;
                                        	}
                                        	bool operator != (const pa2 &p) const{
                                        		return !(abs(x-p.x)==0 && abs(y-p.y)==0);
                                        	}
                                        		
                                        
                                        };
                                        
                                               #define ppa pair<int,pas>
                                        class Point{
                                        	public:
                                        	double x,y;
                                        	Point(double x=0,double y=0):x(x),y(y) {}
                                        	Point operator + (Point p) {return Point(x+p.x,y+p.y);}
                                        	Point operator - (Point p) {return Point(x-p.x,y-p.y);}
                                        	Point operator * (double a) {return Point(x*a,y*a);}
                                        	Point operator / (double a) {return Point(x/a,y/a);}
                                        	double absv() {return sqrt(norm());}
                                        	double norm() {return x*x+y*y;}
                                        	bool operator < (const Point &p) const{
                                        		return x != p.x ? x<p.x: y<p.y;
                                        	}
                                        	bool operator == (const Point &p) const{
                                        		return fabs(x-p.x)<EPS && fabs(y-p.y)<EPS;
                                        	}
                                        };
                                        typedef Point Vector;
                                 #define pl pair<int,pas>
                                        struct Segment{
                                        Point p1,p2;
                                        };
                                         double dot(Vector a,Vector b){
                                        	return a.x*b.x+a.y*b.y;
                                        }
                                        double cross(Vector a,Vector b){
                                        	return a.x*b.y-a.y*b.x;
                                        }
                                    
            bool parareru(Point a,Point b,Point c,Point d){
            //	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
            	return abs(cross(a-b,d-c))<EPS;
            }
            double distance_ls_p(Point a, Point b, Point c) {
              if ( dot(b-a, c-a) < EPS ) return (c-a).absv();
              if ( dot(a-b, c-b) < EPS ) return (c-b).absv();
              return abs(cross(b-a, c-a)) / (b-a).absv();
            }
            bool is_intersected_ls(Segment a,Segment b) {
            	if(a.p1==b.p1||a.p2==b.p1||a.p1==b.p2||a.p2==b.p2) return false;
            	if(parareru((a.p2),(a.p1),(a.p1),(b.p2))&&parareru((a.p2),(a.p1),(a.p1),(b.p1))){
            //		cout<<"sss"<<endl;
            		if(dot(a.p1-b.p1,a.p1-b.p2)<EPS) return true;
            		if(dot(a.p2-b.p1,a.p2-b.p2)<EPS) return true;
            		if(dot(a.p1-b.p1,a.p2-b.p1)<EPS) return true;
            		if(dot(a.p1-b.p2,a.p2-b.p2)<EPS) return true;
            		return false;
            	}
              else return ( cross(a.p2-a.p1, b.p1-a.p1) * cross(a.p2-a.p1, b.p2-a.p1) < EPS ) && ( cross(b.p2-b.p1, a.p1-b.p1) * cross(b.p2-b.p1, a.p2-b.p1) < EPS );
            }
             
            double segment_dis(Segment a,Segment b){
            	if(is_intersected_ls(a,b))return 0;
            	double r=distance_ls_p(a.p1, a.p2, b.p1);
            	r=min(r,distance_ls_p(a.p1, a.p2, b.p2));
            	r=min(r,distance_ls_p(b.p1, b.p2, a.p2));
            	r=min(r,distance_ls_p(b.p1, b.p2, a.p1));
            	return r;
            }
            Point intersection_ls(Segment a, Segment b) {
              Point ba = b.p2-b.p1;
              double d1 = abs(cross(ba, a.p1-b.p1));
              double d2 = abs(cross(ba, a.p2-b.p1));
              double t = d1 / (d1 + d2);
             
              return a.p1 + (a.p2-a.p1) * t;
            }
             
                            string itos( int i ) {
                            ostringstream s ;
                            s << i ;
                            return s.str() ;
                            }
                             
                            int gcd(int v,int b){
                            	if(v>b) return gcd(b,v);
                            	if(v==b) return b;
                            	if(b%v==0) return v;
                            	return gcd(v,b%v);
                            }
             
                            double distans(double x1,double y1,double x2,double y2){
                            	double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
                            	return sqrt(rr);
                            	
                            }
                            
   //         int pr[2000010];
     //       int inv[2000010];
            
            int beki(int wa,int rr,int warukazu){
            	if(rr==0) return 1ll;
            	if(rr==1) return wa%warukazu;
            	if(rr%2==1) return (beki(wa,rr-1,warukazu)*wa)%warukazu;
            	int zx=beki(wa,rr/2,warukazu);
            	return (zx*zx)%warukazu;
            }
            /*
			int comb(int nn,int rr){
				int r=pr[nn]*inv[rr];
				r%=inf;
				r*=inv[nn-rr];
				r%=inf;
				return r;
			}
            
            void gya(int ert){
            	pr[0]=1;
            	for(int i=1;i<ert;i++){
            		pr[i]=(pr[i-1]*i)%inf;
            	}
            	for(int i=0;i<ert;i++) inv[i]=beki(pr[i],inf-2,inf);
            	
            }
             */
			//priority_queue<pa3,vector<pa3>,greater<pa3>> pq;            
             //sort(ve.begin(),ve.end(),greater<int>());
                                     //----------------kokomade tenpure------------
unsigned int randxor()
{
    static unsigned int x=123456789,y=362436069,z=521288629,w=88675123;
    unsigned int t;
    t=(x^(x<<11));x=y;y=z;z=w; return( w=(w^(w>>19))^(t^(t>>8)) );
}

int mask=(1<<8)-1;
int ban[1010][1010]={0};
map<int,int> ma[2][1010];
  signed main(){
  	              cin.tie(0);
    		ios::sync_with_stdio(false);

  	int n,m;
  	cin>>n>>m;
  	
  	for(int i=1;i<=n;i++){
  		string s;
  		
  		cin>>s;
  		s="2"+s;
  		for(int j=1;j<=m;j++)if(s[j]!='.')ban[i][j]=s[j]-'0';
  	}

  	ma[1][1][ban[2][2]?1:0]=0;
  	  	
  	for(int i=1;i<=n;i++){
  		for(int j=1;j<=m;j++)ma[1^(i&1)][j].clear();
  		
  		for(int j=1;j<=m;j++){
  		if(i==n && j==m) break;
  		
  		for(auto it=ma[i&1][j].begin();it!=ma[i&1][j].end();it++){
  			if(i!=n){
  				int B=it->first;
  				int val=it->second;
  		//		cout<<i<<" "<<j<<"   "<<bitset<9>(B)<<" "<<val<<endl;
  				B=B<<3;
  				B&=mask;
  				if(ban[i+2][j-1])B|=4;
  				if(ban[i+2][j])B|=2;
  				if(ban[i+2][j+1])B|=1;
  				
  				if(B&(1<<4))val+=ban[i+1][j],B^=(1<<4);
  				vector<pa> ve;
  				if(B&(1<<1))B^=(1<<1),ve.pb(mp(1,ban[i+2][j]));
  				if(B&(1<<3))B^=(1<<3),ve.pb(mp(3,ban[i+1][j+1]));
  				if(B&(1<<5))B^=(1<<5),ve.pb(mp(5,ban[i+1][j-1]));
  				if(B&(1<<7))B^=(1<<7),ve.pb(mp(7,ban[i][j]));
  				if(ve.size()>1){
  					int l=ve.size();
  					int wa=0;
  					for(auto v:ve)wa+=v.second;
  					for(auto v:ve){
  						int B2=(B|(1<<v.first));
  						int val2=val+wa-v.second;
  						if(ma[1^(i&1)][j].find(B2)==ma[1^(i&1)][j].end()) ma[1^(i&1)][j][B2]=val2;
  						else ma[1^(i&1)][j][B2]=min(ma[1^(i&1)][j][B2],val2);
  					}
  				}
  				else{
  					if(ve.size())B|=(1<<ve[0].first);
  					if(ma[1^(i&1)][j].find(B)==ma[1^(i&1)][j].end()) ma[1^(i&1)][j][B]=val;
  					else ma[1^(i&1)][j][B]=min(ma[1^(i&1)][j][B],val);
  				}
  			}
  			if(j!=m){
  				int B=it->first;
  				int val=it->second;
  				B=B<<1;
  				B&=mask;
  				if(B&1)B^=1;
  				if(B&8)B^=8;
  				if(B&64)B^=64;
  				
  				if(ban[i-1][j+2])B|=64;
  				if(ban[i][j+2])B|=8;
  				if(ban[i+1][j+2])B|=1;
  				
  				if(B&(1<<4))val+=ban[i][j+1],B^=(1<<4);
  				vector<pa> ve;
  				if(B&(1<<1))B^=(1<<1),ve.pb(mp(1,ban[i+1][j+1]));
  				if(B&(1<<3))B^=(1<<3),ve.pb(mp(3,ban[i][j+2]));
  				if(B&(1<<5))B^=(1<<5),ve.pb(mp(5,ban[i][j]));
  				if(B&(1<<7))B^=(1<<7),ve.pb(mp(7,ban[i-1][j+1]));
  			//	if(i==1 && j==1)cout<<ve.size()<<endl;
  				if(ve.size()>1){
  					int l=ve.size();
  					int wa=0;
  					for(auto v:ve)wa+=v.second;
  					for(auto v:ve){
  						int B2=(B|(1<<v.first));
  						int val2=val+wa-v.second;
  						if(ma[i&1][j+1].find(B2)==ma[i&1][j+1].end()) ma[i&1][j+1][B2]=val2;
  						else ma[i&1][j+1][B2]=min(ma[i&1][j+1][B2],val2);
  					}
  				}
  				else{
  					if(ve.size())B|=(1<<ve[0].first);
  					if(ma[i&1][j+1].find(B)==ma[i&1][j+1].end()) ma[i&1][j+1][B]=val;
  					else ma[i&1][j+1][B]=min(ma[i&1][j+1][B],val);
  				}
  			}
  		}
  		}
  	}
  	
  	int lasans=inf;
  	for(auto it=ma[n&1][m].begin();it!=ma[n&1][m].end();it++)lasans=min(lasans,it->second);
  	cout<<lasans<<endl;
  	return 0;
                }
                



Measured memory_bytes: 7920