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

const long long INF = 1e18;
int dr[] = {-1, 1, 0, 0};
int dc[] = {0, 0, -1, 1};

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int r, c;
    if (!(cin >> r >> c)) return 0;
    vector<vector<long long>> grid(r, vector<long long>(c));
    for (int i = 0; i < r; i++) {
        for (int j = 0; j < c; j++) {
            cin >> grid[i][j];
        }
    }
    vector<vector<long long>> dist(r, vector<long long>(c, INF));
    priority_queue<pair<long long, pair<int, int>>, vector<pair<long long, pair<int, int>>>, greater<>> pq;
    dist[0][0] = grid[0][0];
    pq.push({grid[0][0], {0, 0}});
    while (!pq.empty()) {
        auto [d, u] = pq.top();
        pq.pop();
        int cr = u.first;
        int cc = u.second;
        if (d > dist[cr][cc]) continue;
        for (int i = 0; i < 4; i++) {
            int nr = cr + dr[i];
            int nc = cc + dc[i];
            if (nr >= 0 && nr < r && nc >= 0 && nc < c) {
                if (dist[cr][cc] + grid[nr][nc] < dist[nr][nc]) {
                    dist[nr][nc] = dist[cr][cc] + grid[nr][nc];
                    pq.push({dist[nr][nc], {nr, nc}});
                }
            }
        }
    }
    cout << dist[r-1][c-1] << "\n";
    return 0;
}