#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef int64_t lint;
#define rep(i, n) for(int i=0; i<n; i++)
#define repx(i, l, n) for(int i=l; i<n; i++)
#define all(v) v.begin(), v.end()
#define show(x) cout << #x << ": " << x << endl;
#define list(x) cout << #x << ": " << x << "  ";
#define pb push_back
using vi = vector<lint>;
using vvi = vector<vector<lint>>;
template<class T> inline void vin(vector<T>& v) { rep(i, v.size()) cin >> v.at(i); }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<class T> inline void drop(T x) { cout << x << endl; exit(0); }
template<class T> void vout(vector<T> v) { rep(i, v.size()) { cout << v.at(i) << ' '; } cout << endl; }
constexpr lint LINF = LLONG_MAX/2;
#define mp make_pair
using pint = pair<lint, lint>;

vector<vector<pair<lint, lint>>> G;

void dijkstra(lint start, vector<lint> &dist) {
	lint a=0, b=0, x, y, N = G.size();
	dist.resize(N, LINF); dist[start] = 0;
	priority_queue<pint, vector<pint>, greater<pint>> PQ;
	PQ.push(make_pair(0, start));
	while (!PQ.empty()) {
		tie(x, a) = PQ.top(); PQ.pop();
		if (dist[a] < x) continue;
		for (auto p : G[a]) {
			tie(y, b) = p;
			if (chmin(dist[b], x+y)) PQ.push(make_pair(x+y, b));
		}
	}
}

int main() {
	lint N, M;
	cin >> N >> M;
	vvi v(N, vi(M));
	rep(i, N) vin(v[i]);

	lint a=0, b=0, c=0, x, y, z;
	G.resize(N*M*2+2);
	rep(i, M) {
		G[0].pb({0, i+1});
		G[N*M-i].pb({0, N*M*2+1});
	}
	rep(j, M) {
		rep(i, N) {
			G[i*M+j+1].pb({v[i][j], N*M+i*M+j+1});
			G[N*M+i*M+j+1].pb({0, i*M+j+1});
			if (i != N-1) G[N*M+i*M+j+1].pb({v[i+1][j], N*M+(i+1)*M+j+1});
		}
	}
	rep(i, N) {
		rep(j, M-1) {
			G[i*M+j+1].pb({0, i*M+j+2});
			G[i*M+j+2].pb({0, i*M+j+1});
		}
	}
	vi dist;
	dijkstra(0, dist);
	std::cout << dist[N*M*2+1] << '\n';
}