#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i=0;i<(n);i++)
typedef long long ll;
//using mint = modint;
using mint = modint998244353;
using P = pair<int, int>;

const ll INF=1LL<<60, dx[]={0,1,0,-1},dy[]={1,0,-1,0};
bool chmin(ll& a,ll b){if(a>b){a=b; return 1;} return 0;}
bool chmax(ll& a,ll b){if(a<b){a=b; return 1;} return 0;}

int main(){

    int n,m;
    cin >> n >> m;
    vector<vector<ll>> a(n,vector<ll> (m));
    rep(i,n)rep(j,m) cin >> a[i][j];

    vector<vector<ll>> dp(n+1,vector<ll> (m));

    if(n==1) {
        cout << 0 << endl;
        return 0;
    }
    
    ll lowcost = INF;
    rep(j,m){
        dp[2][j] = a[0][j]+a[1][j];
        chmin(lowcost,dp[2][j]); 
    }

    for(int i=3;i<=n;i++){
        ll tmp=INF;
        rep(j,m){
            dp[i][j] = min(lowcost+a[i-2][j],dp[i-1][j]) +a[i-1][j];
            chmin(tmp,dp[i][j]);
        }
        lowcost = tmp;
    }

    ll ans = INF;
    rep(i,m) chmin(ans,dp[n][i]);
    cout << ans << endl;

    return 0;
}