BINLADEN || DIJKSTRA

//Nguyen Huu Hoang Minh
#include <bits/stdc++.h>
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define reset(x) memset(x, 0,sizeof(x))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define N 22299
#define remain(x) if (x > MOD) x -= MOD
#define ii pair<int, int>
#define vi vector<int>
#define vii vector< ii >
#define bit(x, i) (((x) >> (i)) & 1)
#define Task "test"
#define int long long

using namespace std;

typedef long double ld;

int n,m;
int node = 0;
int st, en;
int d[2222*10+999];
vector<ii> a[N];
int even[2225][15];
int odd[2225][15];

void readfile()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    if (fopen(Task".inp","r"))
    {
        freopen(Task".inp","r",stdin);
        //freopen(Task".out","w",stdout);
    }
    cin >> m >> n;
    st = 1;
    en = (m+1)*n;
    for(int i=1; i<=2*m; i++)
    {
        if (i%2){
            int floor = i/2 + 1;
            for(int j=1; j<=n; j++) cin >> even[floor][j];
        }
        else{
            int floor = i/2;
            for(int j=1; j<n; j++) cin >> odd[floor][j];
        }
    }
    for(int i=1; i<=m; i++)
    {
        for(int j=1; j<=n; j++)
        {
            int u = i*n + j;
            int uup = (i-1)*n + j;
            a[u].pb(ii(uup,even[i][j]));
            a[uup].pb(ii(u,even[i][j]));
            int udown = (i+1)*n+j;
            a[u].pb(ii(udown,even[i+1][j]));
            a[udown].pb(ii(u,even[i+1][j]));
            if (j==1){
                int v = u+1;
                a[u].pb(ii(v,odd[i][j]));
                a[v].pb(ii(u,odd[i][j]));
            }
            else if (j==n)
            {
                int v = u-1;
                a[u].pb(ii(v,odd[i][j-1]));
                a[v].pb(ii(u,odd[i][j-1]));
            }
            else{
                int v = u+1;
                a[u].pb(ii(v,odd[i][j]));
                a[v].pb(ii(u,odd[i][j]));
                v = u-1;
                a[u].pb(ii(v,odd[i][j-1]));
                a[v].pb(ii(u,odd[i][j-1]));
            }
        }
    }
}

void dijkstra()
{
    priority_queue<ii, vii, greater<ii>> q;
    for(int i=1; i<=en; i++) d[i] = 99999999999;
    for(int i=1; i<=n; i++) d[i] = 0, q.push(ii(0,i));
    while (q.size())
    {
        int u = q.top().se;
        int du = q.top().fi;
        q.pop();
        if (du != d[u]) continue;
        for(auto i : a[u])
        {
            int v = i.fi;
            int uv = i.se;
            if (d[v] > d[u] + uv)
            {
                d[v] = d[u] + uv;
                q.push(ii(d[v],v));
            }
        }
    }
}

void proc()
{
    dijkstra();
    cout << d[en];
}

signed main()
{
    readfile();
    proc();
    return 0;
}