// Slower C++ solution:
#include<cstdio>

#include<cstdlib>

#include<iostream>

#include<cmath>

#include<algorithm>

#include<cstring>

#include<queue>

#define IL inline

#define RG register

#define inf 0x3f3f3f3f

#define LL long long

#define N 10005

#define M 20005

using namespace std;

IL int gi()

{

	RG int res=0,s=1;RG char ch;

	for(ch=getchar(); (ch<'0'||ch>'9')&&ch!='-' ;ch=getchar());

	if(ch=='-') s=-1,ch=getchar();

	for(;ch>='0'&&ch<='9';ch=getchar()) res=10*res+ch-48;

	return res*s;

}

int n,m,head[N],edge[2*M][5],num=-1;

int dis[N],flag[N],ans=0,a[N];

struct node

{

	int d,v;

	node(RG int dd=0,RG int vv=0){d=dd,v=vv;}

	bool operator < (const node &o) const{

		return v>o.v;

	}

};

priority_queue<node>heap;

IL void adde(RG int u,RG int v,RG int d,RG int c)

{

	edge[++num][0]=v;edge[num][1]=head[u];head[u]=num;edge[num][2]=d,edge[num][3]=c,edge[num][4]=0;

	edge[++num][0]=u;edge[num][1]=head[v];head[v]=num;edge[num][2]=d,edge[num][3]=c,edge[num][4]=0;

}

IL void init(){

	memset(head,-1,sizeof(head)); num=-1; ans=0;

	memset(dis,inf,sizeof(dis));

	memset(flag,0,sizeof(flag));

}

IL int cmp(RG int x,RG int y){return dis[x]<dis[y];}

IL void work1()

{

	RG int p;

	dis[1]=0; heap.push(node(1,0));

	while(!heap.empty())

		{

			p=heap.top().d; heap.pop();

			while(flag[p]&&!heap.empty()) p=heap.top().d,heap.pop();

			if(flag[p]) break; flag[p]=1;

			for(RG int i=head[p];i!=-1;i=edge[i][1]){

				if(dis[edge[i][0]]>dis[p]+edge[i][2]){

					dis[edge[i][0]]=dis[p]+edge[i][2];

					heap.push(node(edge[i][0],dis[edge[i][0]]));

				}

			}

		}

	RG int mn;

	for(RG int i=1;i<=n;++i) a[i]=i;

	sort(a+1,a+n+1,cmp);

	for(RG int i=2;i<=n;++i)

		{

			mn=inf;

			for(RG int j=head[i];j!=-1;j=edge[j][1])

				{

					if(dis[i]==dis[edge[j][0]]+edge[j][2])

						mn=min(mn,edge[j][3]);

				}

			ans+=mn;

		}

	printf("%d\n",ans);

}

int main()

{

	//freopen("1.in","r",stdin);

	//freopen("1.out","w",stdout);

	RG int u,v,d,c;

	while(true)

		{

			n=gi(),m=gi(); if(!n&&!m) break; init();

			for(RG int i=1;i<=m;++i)

				u=gi(),v=gi(),d=gi(),c=gi(),adde(u,v,d,c);

			work1();

		}

	//fclose(stdin);fclose(stdout);

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.154748827040756x):
#include <bits/stdc++.h>

using namespace std;



#define db double

#define ll long long

#define RG register



inline int gi()

{

	RG int ret; RG bool flag; RG char ch;

	ret=0, flag=true, ch=getchar();

	while (ch < '0' || ch > '9')

		ch == '-' ? flag=false : 0, ch=getchar();

	while (ch >= '0' && ch <= '9')

		ret=(ret<<3)+(ret<<1)+ch-'0', ch=getchar();

	return flag ? ret : -ret;

}



const db pi = acos(-1.0);

const int N = 142857, inf = 1<<30;



int f[N],et[N],ed[N],nx[N],ew[N],dis[N],cst[N];

bool vis[N];

queue <int> q;

int num;



inline void add(int x,int y,int z,int w)

{

	et[++num]=y, nx[num]=f[x], ed[num]=z, ew[num]=w, f[x]=num;

}



int main()

{

	int n,m,i,x,y,z,w;

	while (true)

		{

			n=gi(), m=gi();

			if (n == 0)

				break;

			for (i=1; i<=m; ++i)

				{

					x=gi(), y=gi(), z=gi(), w=gi();

					add(x,y,z,w), add(y,x,z,w);

				}

			for (i=2; i<=n; ++i)

				cst[i]=dis[i]=inf;

			q.push(1), vis[1]=true;

			while (!q.empty())

				{

					x=q.front(), q.pop(), vis[x]=false;

					for (i=f[x]; i; i=nx[i])

						{

							y=et[i], z=ed[i], w=ew[i];

							if (dis[y] > dis[x]+z)

								{

									dis[y]=dis[x]+z;

									cst[y]=cst[x]+w;

									if (!vis[y])

										q.push(y), vis[y]=true;

								}

							if (dis[y] == dis[x]+z && cst[y] > w)

								cst[y]=w;

						}

				}

			x=0;

			for (i=2; i<=n; ++i)

				x+=cst[i];

			printf("%d\n",x);

			for (i=1; i<=n; ++i)

				f[i]=0;

			num=0;

		}

	return 0;

}