#include<bits/stdc++.h>
// #include<atcoder/all>
// #include<boost/multiprecision/cpp_int.hpp>

using namespace std;
// using namespace atcoder;
// using bint = boost::multiprecision::cpp_int;
using ll = long long;
using ull = unsigned long long;
using P = pair<int,int>;
#define rep(i,n) for(ll i = 0;i < (ll)n;i++)
#define ALL(x) (x).begin(),(x).end()
#define MOD 1000000007
// #define MOD 998244353


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];
  if(n == 1){
    cout << "0\n";
    return 0;
  }
  vector<ll> dp(m);
  rep(i,m)dp[i] = a[0][i];
  for(int i = 1;i < n;i++){
    vector<ll> DP(m);
    ll k = *min_element(ALL(dp));
    rep(j,m)DP[j] = min(k + a[i][j] + a[i-1][j],dp[j] + a[i][j]);
    swap(dp,DP);
  }
  cout << *min_element(ALL(dp)) << "\n";
  

  return 0;
}