#include<stdio.h>
#include<string.h>
#define CR 12
#define CC 102
#define MAX 2147483646

int map[CR][CC];
int R,C;

int S[CR][CC];
int Path[CR][CC];

void ini(void){
    int i,j;
    for(i = 0; i < CR;i++)
        for(j =0; j < CC;j++){
            S[i][j] = -1;
            Path[i][j] = -1;
        }
}

int Go[3][2] = {{0,+1},{+1,+1},{-1,+1}};



int Dp(int r,int c,int p){
    int i;
    int cr = MAX;
    if(S[r][c] != -1) return S[r][c];
    int cost = map[r][c];
    bool t = true;
    for(i = 0; i < 3; i++){
        int nr = Go[i][0] + r;
        int nc = Go[i][1] + c;
        if(nr < 0 || nr >= R || nc < 0 || nc >= C) continue;
        t = false;
        int nrr = cost +  Dp(nr,nc,c);
        if(nrr < cr) cr = nrr;
    }
    if(r == 0){
        t = false;
        int ct = cost + Dp(R,c+1,c);
        if(ct < cr) cr = ct;
    }
    else if(r == R-1){
        t = false;
        int ct = cost + Dp(0,c+1,c);
        if(ct < cr) cr = ct;
    }


    if(t) {
        cr = cost;
    }
    S[r][c] = cr;
    return S[r][c];

}

int main(){
    scanf("%d %d",&R,&C);
    int i,j;
    ini();
    for(i = 0; i < R; i++)
        for(j = 0; j < C; j++)
            scanf("%d",&map[i][j]);
        int inf = MAX;
        for(i = 0; i < R; i++){
            int RE = Dp(i,0,i);
            if(RE < inf)
                inf = RE;
        }
        printf("%d\n",inf);




    return 0;
}