#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for (int i = 0; i < (long long)(n); i++)
#define rep2(i, m ,n) for (int i = (m); i < (long long)(n); i++)
#define REP(i, n) for (int i = 1; i < (long long)(n); i++)
typedef long long ll;

#define updiv(N,X) (N + X - 1) / X
#define l(n) n.begin(),n.end()

#define YesNo(Q) Q==1?cout<<"Yes":cout<<"No"
using P = pair<int, int>;
using mint = modint998244353;
const int MOD = 998244353LL;
const ll INF = 999999999999LL;
vector<long long> fact, fact_inv, inv;
/*  init_nCk :二項係数のための前処理
    計算量:O(n)
*/
void init_nCk(int SIZE) {
    fact.resize(SIZE + 5);
    fact_inv.resize(SIZE + 5);
    inv.resize(SIZE + 5);
    fact[0] = fact[1] = 1;
    fact_inv[0] = fact_inv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < SIZE + 5; i++) {
        fact[i] = fact[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
        fact_inv[i] = fact_inv[i - 1] * inv[i] % MOD;
    }
}
/*  nCk :MODでの二項係数を求める(前処理 int_nCk が必要)
    計算量:O(1)
*/
long long nCk(int n, int k) {
    assert(!(n < k));
    assert(!(n < 0 || k < 0));
    return fact[n] * (fact_inv[k] * fact_inv[n - k] % MOD) % MOD;
}

long long modpow(long long a, long long n, long long mod) {
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

 

int main() {
int n,m;cin>>n>>m;
ll v[n][m];
vector<ll>mns(n,999999999LL);  
  
  rep(i,n){rep(j,m){cin>>v[i][j];}}
  vector<vector<ll>>dp(n,vector<ll>(m,0LL));
  rep(i,n){
    rep(j,m){
      if(i==0){dp[i][j]=v[i][j];continue;}
      dp[i][j]=min(mns[i-1]+v[i-1][j]+v[i][j],v[i][j]+dp[i-1][j]);mns[i]=min(mns[i],dp[i][j]);}
  }
  //rep(i,n){rep(j,m){cout<<dp[i][j]<<" ";}cout<<endl;}
  if(n==1){cout<<0<<endl;return 0;}
  cout << mns[n-1] << endl;return 0;
}