#include<bits/stdc++.h>
#if __has_include(<atcoder/all>)
#endif
using namespace std;
#define eb emplace_back
#define LL(...) ll __VA_ARGS__;lin(__VA_ARGS__)
#define RDVV(T,n,...) vec<T>__VA_ARGS__;fe(refs(__VA_ARGS__),e)e.get().resizes(n);vin(__VA_ARGS__)
#define VV(n,...) RDVV(ll,n,__VA_ARGS__)
#define fo(i,...) for(auto[i,i##stop,i##step]=for_range<ll>(0,__VA_ARGS__);i<i##stop;i+=i##step)
#define fe(a,e,...) for(auto&&__VA_OPT__([)e __VA_OPT__(,__VA_ARGS__]):a)
#define defpp template<ostream&o=cout>void pp(const auto&...a){[[maybe_unused]]const char*c="";((o<<c<<a,c=" "),...);o<<'\n';}void epp(const auto&...a){pp<cerr>(a...);}
#define entry defpp void main();void main2();}int main(){my::io();my::main();}namespace my{
namespace my{
void io(){cin.tie(nullptr)->sync_with_stdio(0);cout<<fixed<<setprecision(15);}
using ll=long long;
constexpr auto refs(auto&...a){return array{ref(a)...};}
template<class T>constexpr auto for_range(T s,T b){T a=0;if(s)swap(a,b);return array{a-s,b,1-s*2};}
void lin(auto&...a){(cin>>...>>a);}
void vin(auto&...a){fo(i,(a.size()&...))(cin>>...>>a[i]);}
constexpr ll size10(auto x){x|=1;ll r=0;while(x>0)x/=10,++r;return r;}
template<class T>constexpr ll maxsize10(){return size10(numeric_limits<T>::max());}
bool amin(auto&a,const auto&b){return b<a?a=b,1:0;}
template<class A,class B=A>struct pair{
  A a;B b;
  pair()=default;
  pair(A a,B b):a(a),b(b){}
  auto operator<=>(const pair&)const=default;
};
template<bool is_negative=false>struct infinity{
  template<integral T>static constexpr T ones(size_t n){return n?ones<T>(n-1)*10+1:0;}
  template<integral T>constexpr operator T()const{static constexpr T v=ones<T>(maxsize10<T>())*(1-is_negative*2);return v;}
  template<class T>constexpr bool operator==(const T&x)const{return static_cast<T>(*this)==x;}
};
constexpr infinity oo;
void dec(auto&...a){((--a),...);}
auto&rev(auto&a){ranges::reverse(a);return a;}
template<class...A>using pack_back_t=tuple_element_t<sizeof...(A)-1,tuple<A...>>;
}
namespace my{
template<class V>constexpr int depth=0;
template<class T>struct core_t_helper{using type=T;};
template<class T>using core_t=core_t_helper<T>::type;
template<class V>struct vec;
template<int D,class T>struct hvec_helper{using type=vec<typename hvec_helper<D-1,T>::type>;};
template<class T>struct hvec_helper<0,T>{using type=T;};
template<int D,class T>using hvec=hvec_helper<D,T>::type;
template<class V>struct vec:vector<V>{
  static constexpr int D=depth<V>+1;
  using C=core_t<V>;
  using vector<V>::vector;
  void resizes(const auto&...a){if constexpr(sizeof...(a)==D)*this=make(a...,C{});else{ }}
  static auto make(ll n,const auto&...a){
    if constexpr(sizeof...(a)==1)return vec<C>(n,array{a...}[0]);
    else { }
  }
  vec&operator--(){fe(*this,e)--e;return*this;}
  ll size()const{return vector<V>::size();}
  auto&emplace_back(auto&&...a){vector<V>::emplace_back(std::forward<decltype(a)>(a)...);return*this;}
};
template<class...A>requires(sizeof...(A)>=2)vec(const A&...a)->vec<hvec<sizeof...(A)-2,pack_back_t<A...>>>;
}
namespace my{
template<class T>struct queue:std::queue<T>{
  queue(const initializer_list<T>&a={}){fe(a,e)this->emplace(e);}
  ll size()const{return std::queue<T>::size();}
  T pop(){T r=this->front();std::queue<T>::pop();return r;}
};
template<class T,class F>struct priority_queue:std::priority_queue<T,vector<T>,F>{
  priority_queue(const initializer_list<T>&a={}){fe(a,e)this->emplace(e);}
  ll size()const{return std::priority_queue<T,vector<T>,F>::size();}
  T pop(){T r=this->top();std::priority_queue<T,vector<T>,F>::pop();return r;}
};
template<class T>using min_heap=priority_queue<T,greater<T>>;
}
namespace my{
template<class WT>struct Edge{
  int from_,to_;
  WT wt_;
  int id_;
  Edge()=default;
  Edge(int from,int to,WT wt=1,int id=-1):from_(from),to_(to),wt_(wt),id_(id){}
  auto operator<=>(const Edge&e)const{return wt_<=>e.wt_;}
};
template<class WT>class RootedTree{
public:
  ll n_;
  vec<vec<Edge<WT>>>edges_;
  vec<Edge<WT>>rev_edge_;
  int root_;
  RootedTree(ll n,ll r):n_(n),edges_(n),rev_edge_(n,{-1,-1,WT{},-1}),root_(r){}
  ll size()const{return n_;}
  auto par(ll u)const{return u==root_?-1:rev_edge_[u].from_;}
  auto root_child_enumerate()const{
    vec<ll>res(size(),-1);
    fe(bfs_order(root_),u){
      if(u==root_)continue;
      if(par(u)==root_)res[u]=u;
      fe(edges_[u],e)res[e.to_]=res[u];
    }
    return res;
  }
  void set_edge(const Edge<WT>&e){
    edges_[e.from_].eb(e);
    rev_edge_[e.to_]=e;
  }
  auto bfs_order(ll start=-1)const{
    if(start==-1)start=root_;
    vec<ll>ord;
    queue<ll>q{start};
    while(q.size()){
      ll u=q.pop();
      ord.eb(u);
      fe(edges_[u],e)q.emplace(e.to_);
    }
    return ord;
  }
};
}
namespace my{
template<class WT>class Graph{
public:
  ll n_;
  vec<vec<Edge<WT>>>edges_;
  Graph()=default;
  Graph(ll n):n_(n),edges_(n){}
  decltype(auto)operator[](ll i)const{return edges_[i];}
  ll size()const{return edges_.size();}
  auto&add_edges(const vec<ll>&a,const vec<ll>&b,const vec<WT>&w){fo(i,a.size())edges_[a[i]].eb(a[i],b[i],w[i],i);return*this;}
  vec<int>buf;
  int count=0;
  auto dijkstra_tree(int s)const{
    RootedTree<WT>tree(n_,s);
    vec<WT>dist(n_,oo);
    dist[s]=WT{};

    vec<bool>used(n_);
    min_heap<pair<WT,Edge<WT>>>q{{WT{},{-1,s,WT{},-1}}};
    while(q.size()){
      auto[du,pu]=q.pop();
      auto u=pu.to_;
      if(dist[u]<du)continue;
      if(used[u])continue;
      used[u]=1;

      if(pu.from_!=-1)tree.set_edge(pu);

      fe(edges_[u],e){
        if(amin(dist[e.to_],dist[u]+e.wt_)){
          assert(e.wt_>=WT{});
          assert(!used[e.to_]);
          q.emplace(dist[e.to_],e);
        }
      }
    }
    return tree;
  }
  auto dijkstra_dist_enumerate(int s)const{
    vec<WT>dist(n_,oo);
    dist[s]=WT{};

    vec<bool>used(n_);
    min_heap<pair<WT,Edge<WT>>>q{{WT{},{-1,s,WT{},-1}}};
    while(q.size()){
      auto[du,pu]=q.pop();
      auto u=pu.to_;
      if(dist[u]<du)continue;
      if(used[u])continue;
      used[u]=1;

      fe(edges_[u],e){
        if(amin(dist[e.to_],dist[u]+e.wt_)){
          assert(e.wt_>=WT{});
          assert(!used[e.to_]);
          q.emplace(dist[e.to_],e);
        }
      }
    }
    return dist;
  }
};
}
namespace my{
template<class WT>auto undirected_shortest_cycle(const Graph<WT>&g,ll s){

  auto dist=g.dijkstra_dist_enumerate(s);
  auto spt=g.dijkstra_tree(s);

  WT cost=oo;
  ll a=-1,b=-1;
  vec mi(g.size(),WT{oo});
  fe(g[s],e){
    if(e.to_==s){
      if(amin(cost,e.wt_))a=b=s;
      continue;
    }

    if(mi[e.to_]==oo)mi[e.to_]=e.wt_;
    else if(amin(cost,mi[e.to_]+e.wt_))a=s,b=e.to_;
  }

  auto roch=spt.root_child_enumerate();
  fo(u,g.size()){
    if(u==s)continue;
    if(dist[u]==oo)continue;
    fe(g[u],e){
      if(e.to_==s)continue;
      if(dist[e.to_]==oo)continue;
      if(roch[u]==roch[e.to_])continue;
      if(amin(cost,dist[u]+dist[e.to_]+e.wt_))a=u,b=e.to_;
    }
  }

  vec<ll>cycle;
  while(a!=-1&&a!=s)cycle.eb(a),a=spt.par(a);
  cycle.eb(s);
  rev(cycle);
  while(b!=-1&&b!=s)cycle.eb(b),b=spt.par(b);
  return pair{cycle,cost};
}
template<class WT>auto directed_shortest_cycle(const Graph<WT>&g,ll s){
  auto dist=g.dijkstra_dist_enumerate(s);
  auto spt=g.dijkstra_tree(s);

  WT cost=oo;
  ll a=-1;
  fo(u,g.size())fe(g[u],e)if(e.to_==s&&amin(cost,dist[u]+e.wt_))a=u;

  vec<ll>cycle;
  while(a!=-1&&a!=s)cycle.eb(a),a=spt.par(a);
  cycle.eb(s);
  return pair{rev(cycle),cost};
}
}
namespace my{entry
void main(){
  LL(T,N,M);
  VV(M,a,b,c);dec(a,b);
  Graph<ll>g(N);

  ll ans=oo;
  if(T==0){
    g.add_edges(a,b,c);
    g.add_edges(b,a,c);
    fo(i,N)amin(ans,undirected_shortest_cycle(g,i).b);
  }else{
    g.add_edges(a,b,c);
    fo(i,N)amin(ans,directed_shortest_cycle(g,i).b);
  }
  pp(ans!=oo?ans:-1);
}}