#include <bits/stdc++.h>
using namespace std;

#define taskname "TEST"
typedef long long ll;
typedef long double ld;
typedef pair <ll, int> lli;
#define fi first
#define se second
#define fast_io ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)

const int N = 3e4 + 5;
const ll INF = 1e18;

ll d[N];
int n, m;
vector <lli> adj[N];

void inp() {
    cin >> m >> n;
    for (int i = 1; i <= m; i++) {
        int w;
        for (int j = 1; j <= n; j++) {
            cin >> w;
            adj[i*n + j].push_back(lli(w, (i - 1)*n + j));
        }
        for (int j = 1; j < n; j++) {
            cin >> w;
            adj[i*n + j].push_back(lli(w, i*n + j + 1));
            adj[i*n + j + 1].push_back(lli(w, i*n + j));
        }
    }
}
void dijktra() {
    priority_queue <lli, vector <lli>, greater <lli> > pq;
    for (int i = 1; i <= n*m + n; i++) d[i] = INF;
    d[m*n + n] = 0;
    pq.push(lli(0, m*n + n));
    while (pq.size()) {
        lli t = pq.top();
        pq.pop();
        int u = t.se;
        if (d[u] < t.fi) continue;
        for (lli t: adj[u])
            if (d[t.se] > d[u] + t.fi) {
                d[t.se] = d[u] + t.fi;
                pq.push(lli(d[t.se], t.se));
            }
    }
}
void out() {
    cout << *min_element(d + 1, d + n + 1);
}

int main() {
    fast_io;
//    freopen(taskname".INP", "r", stdin);
//    freopen(taskname".OUT", "w", stdout);
    inp();
    dijktra();
    out();
}