#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000000000000

pair<long long,vector<int>> get(auto E){
	vector<long long> dis(E.size(),Inf);
	dis[0] = 0LL;
	
	priority_queue<pair<long long,int>,vector<pair<long long,int>>,greater<pair<long long,int>>> Q;
	Q.emplace(0,0);
	vector<int> last(E.size(),-1);
	while(Q.size()>0){
		long long D = Q.top().first;
		int u = Q.top().second;
		Q.pop();
		if(D!=dis[u])continue;
		
		rep(i,E[u].size()){
			int v = E[u][i].first;
			long long DD = E[u][i].second;
			if(dis[v]>D+DD){
				dis[v] = D+DD;
				Q.emplace(D+DD,v);
				last[v] = u;
			}
		}
	}
	
	vector<int> ret(1,E.size()-1);
	while(ret.back()!=0){
		ret.push_back(last[ret.back()]);
	}
	
	return make_pair(dis.back(),ret);
}

int main(){
	
	int N,M;
	cin>>N>>M;
	
	vector E(N,vector<pair<int,long long>>());
	auto Ec = E;
	
	rep(i,M){
		int u,v,c,d;
		scanf("%d %d %d %d",&u,&v,&c,&d);
		u--;v--;
		
		E[u].emplace_back(v,c);
		E[v].emplace_back(u,c);
		Ec[u].emplace_back(v,d);
		Ec[v].emplace_back(u,d);
	}
	
	long long ans = 0LL;
	//cout<<'a'<<endl;
	auto ret = get(E);
	ans += ret.first;
	
	rep(i,ret.second.size()-1){
		int u = ret.second[i],v = ret.second[i+1];
		rep(j,E[u].size()){
			if(E[u][j].first==v)swap(E[u][j],Ec[u][j]);
		}
		
		rep(j,E[v].size()){
			if(E[v][j].first==u)swap(E[v][j],Ec[v][j]);
		}
	}
	
	ans += get(E).first;
	
	cout<<ans<<endl;
	
    return 0;
}