#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int,int>
#define pil pair<int,ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int,int>>
#define vpll vector<pair<ll,ll>>
#define vvpii vector<vector<pair<int,int>>>
#define vvpll vector<vector<pair<ll,ll>>>

template<typename T> void debug(T e){
    cerr << e << endl;
}

template<typename T> void debug(vector<T> &v){
    rep(i, v.size()){
        cerr << v[i] << " ";
    }
    cerr << endl;
}

template<typename T> void debug(vector<vector<T>> &v){
    rep(i, v.size()){
        rep(j, v[i].size()){
            cerr << v[i][j] << " ";
        }
        cerr << endl;
    }
}

template<typename T> void debug(vector<pair<T, T>> &v){
    rep(i,v.size()){
        cerr << v[i].first << " " << v[i].second << endl;
    }
}

template<typename T> void debug(set<T> &st){
    for (auto itr = st.begin(); itr != st.end(); itr++){
        cerr << *itr << " ";
    }
    cerr << endl;
}

template<typename T> void debug(multiset<T> &ms){
    for (auto itr = ms.begin(); itr != ms.end(); itr++){
        cerr << *itr << " ";
    }
    cerr << endl;
}

template<typename T> void debug(map<T, T> &mp){
    for (auto itr = mp.begin(); itr != mp.end(); itr++){
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out(){
    cerr << endl;
}

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T){
    cerr << H << " ";
    debug_out(T...);
}


int main(){
    ll N,M;
    cin >> N >> M;
    vvl A(N, vl(M));
    rep(i,N){
        rep(j,M){
            cin >> A[i][j];
        }
    }
    if (N == 1){
        cout << 0 << endl;
        return 0;
    }
    ll INF = 10000000000000000;
    vvl dp(N, vl(M, INF));
    for (ll i = 0; i < N; i++){
        ll min_val = INF;
        if (i == 0){
            min_val = 0;
        }
        else{
            for (ll j = 0; j < M; j++){
                min_val = min(min_val, dp[i - 1][j]);
            }
        }
        if (i == 0){
            for (ll j = 0; j < M; j++){
                dp[i][j] = A[i][j];
            }
        }
        else{
            for (ll j = 0; j < M; j++){
                dp[i][j] = min(dp[i][j], min(dp[i - 1][j] + A[i][j], min_val + A[i - 1][j] + A[i][j]));
            }
        }
    }
    ll ans = INF;
    for (ll j = 0; j < M; j++){
        ans = min(ans, dp[N - 1][j]);
    }
    //debug(dp);
    cout << ans << endl;
}