#include <bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,b,a) for(int i=b;i>=a;i--)
#define fori(a) for(auto i : a )
#define all(a) begin(a), end(a)
#define set(a,b) memset(a,b,sizeof(a))
#define sz(a) a.size()
double pi=acos(-1);
#define ll long long
#define ull unsigned long long
#define pb push_back
#define PF push_front //deque
#define mp make_pair
#define pq priority_queue
const ll mod=1e9;
#define f first
#define s second
#define pii pair< int, int >
#define vi vector<int>
#define vpii vector<pii>
#define debug(v) for(auto i:v) cout<<i<<" ";
#define tc int t; cin >> t; while(t--)

using namespace std;
void optimizeIO(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}
const int N=100000;
vector<set<int>> graph(N);
void solve(){
  int n,k,m;
  cin>>n>>k>>m;
  rep(i,0,m){
    vector<int> v1(k);
    rep(j,0,k)  cin>>v1[j];

    rep(j,0,k){
      rep(l,j+1,k){
        graph[v1[j]-1].insert(v1[l]-1);
        graph[v1[l]-1].insert(v1[j]-1);
      }
    }
  }
  vector<ll> dis(n,1e18);
  dis[0]=1;
  rep(i,0,n){
    for(auto j:graph[i]){
      if(j!=i) dis[j]=min(dis[j],dis[i]+1);
    }
  }
  if(dis[n-1]==1e18) cout<<-1<<endl;
  else cout<<dis[n-1]<<endl;
}
int main(){
    optimizeIO();
    {solve();}
}

#include <bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,b,a) for(int i=b;i>=a;i--)
#define fori(a) for(auto i : a )
#define all(a) begin(a), end(a)
#define set(a,b) memset(a,b,sizeof(a))
#define sz(a) a.size()
double pi=acos(-1);
#define ll long long
#define ull unsigned long long
#define pb push_back
#define PF push_front //deque
#define mp make_pair
#define pq priority_queue
const ll mod=1e9;
#define f first
#define s second
#define pii pair< int, int >
#define vi vector<int>
#define vpii vector<pii>
#define debug(v) for(auto i:v) cout<<i<<" ";
#define tc int t; cin >> t; while(t--)
using namespace std;
void optimizeIO(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}


const int N=100000;
vector<set<int>> graph(N);
struct dsu{
  vector<ll> par,rank;
  dsu(ll n):rank(n,1),par(n,1){
    rep(i,0,n) par[i]=i;
  }
  ll root(ll a){
    if(a==par[a]) return a;
    return par[a]=root(par[a]);
  }
  void merge(ll a, ll b){
    a=root(a);
    b=root(b);
    if(a==b) return;
    if(rank[a]<rank[b]) swap(a,b);
    par[b]=a;
    rank[a]+= rank[b];
  }
};
void solve(){
  int n,k,m;
  cin>>n>>k>>m;
  rep(i,0,m){
    vector<int> v1(k);
    rep(j,0,k)  cin>>v1[j];
    rep(j,0,k) rep(l,0,k) if(j!=l) graph[v1[j]-1].insert(v1[l]-1);
  }

  dsu d(n);
  rep(i,0,n) for(auto j:graph[i]) d.merge(i,j);
  if(d.root(n-1)!=d.root(0)){
    cout<<-1<<endl;
    return;
  }

  vector<ll> dis(n,1e18);
  vector<ll> vis(n,0);
  dis[0]=1;
  priority_queue<pii,vector<pii>,greater<pii>> pq;
  pq.push({1,0});

  while(!pq.empty()){
    pii x=pq.top();
    pq.pop();
    if(x.s==n-1){
      cout<<dis[n-1]<<endl;
      return;
    }
    if(vis[x.s]==1) continue;
    vis[x.s]=1;
    for(auto j:graph[x.s])
      if(dis[j]> 1+x.f){
        dis[j]=1+x.f;
        pq.push({dis[j],j});
      }
  }
}
int main(){
    optimizeIO();
    solve();
}