#include<bits/stdc++.h>
//#pragma GCC optimize(2)
#define int long long
#define INF LLONG_MAX
#define ios ios::sync_with_stdio(0),cout.tie(0),cin.tie(0);
using namespace std;
inline int read(){int x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if (ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=x*10+ch-48;ch=getchar();}return x*f;}
const int N=3e5+10;
struct node{
    int x,y,v;
}a[N];
int fa[N],n,m,cnt=1,sum,idx;
bool cmp(node x,node y){return x.v<y.v;}
int find(int x){
    if(x==fa[x])return x;
    return fa[x]=find(fa[x]);
}
void he(int x,int y){
    int fx=find(x),fy=find(y);
    if(fx!=fy)fa[fx]=fy;
}
void k(){
    for(int i=0;i<=n;i++)fa[i]=i;
    sort(a+1,a+idx+1,cmp);
    int i=1;
    while(i<=idx&&cnt<=m){
        if(find(a[i].x)!=find(a[i].y)){
            cnt++;
            sum+=a[i].v;
            he(a[i].x,a[i].y);
        }
        i++;
    }
}
signed main(){
    ios
    cin>>n>>m;
    for(int i=1;i<=m;i++)a[++idx]={0,i,n};
    for(int i=1;i<=m;i++){
        for(int j=1;j<=m;j++){
            int c;
            cin>>c;
            if(i<j&&c!=0)a[++idx]={i,j,c};
        }
    }
    k();
    cout<<sum;
    return 0;
}