// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;



typedef long long ll;

const int N = 10005;

const int M = 1000000007;



int n, m;

typedef int wtype;

struct Edge { int v; wtype d, c; };

vector<Edge> e[N];

wtype dist[N], cost[N];

int pre[N];

bool vis[N];

int SPFA(int src) {

  memset(dist, 0x3f, sizeof(dist)); dist[src] = 0;

  memset(cost, 0x3f, sizeof(cost)); cost[src] = 0;

  memset(vis, 0, sizeof(vis)); vis[src] = true;

  stack<int> que; que.push(src);

  while (!que.empty()) {

    int u = que.top(); que.pop();

    vis[u] = false;

    for (int i = 0; i < (int)e[u].size(); i++) {

      int v = e[u][i].v; wtype d = e[u][i].d, c = e[u][i].c;

      if (dist[v] > dist[u] + d || (dist[v] == dist[u] + d && cost[v] != 0x3f3f3f3f && cost[v] > c)) {

        dist[v] = dist[u] + d; cost[v] = c;

        if (!vis[v]) { vis[v] = true; que.push(v); }

      }

    }

  }

  int ret = 0;

  for (int i = 1; i <= n; i++) { ret += cost[i]; }

  return ret;

}



int main() {

  while (scanf("%d%d", &n, &m), n) {

    for (int i = 1; i <= n; i++) { e[i].clear(); }

    for (int i = 0, u, v, d, c; i < m; i++) {

      scanf("%d%d%d%d", &u, &v, &d, &c);

      e[u].push_back((Edge) {v, d, c});

      e[v].push_back((Edge) {u, d, c});

    }

    printf("%d\n", SPFA(1));

  }

}

// Faster C++ solution for the same problem (measured speedup: 1.3700791441289824x):
//#include<bits/stdc++.h>

#define _CRT_SBCURE_NO_DEPRECATE

#include <set>

#include <map>

#include <cmath>

#include <queue>

#include <stack>

#include <vector>

#include <string>

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <iostream>

#include <algorithm>

#include <functional>

//#define UP(i,x,y) for(int i=x;i<=y;i++)

//#define DOWN(i,x,y) for(int i=x;i>=y;i--)

#define sdddd(x,y,z,k) scanf("%d%d%d%d", &x, &y, &z, &k)

#define sddd(x,y,z) scanf("%d%d%d", &x, &y, &z)

#define sdd(x,y) scanf("%d%d", &x, &y)

#define sd(x) scanf("%d", &x)

#define mp make_pair

#define pb push_back

#define lson k<<1

#define rson k<<1|1

#define mid (l+r)/2

#define ms(x, y) memset(x, y, sizeof x)

using namespace std;

typedef long long ll;

//typedef unsigned long long ull;

#define MOD 142857

const int maxn = 10100;

const int INF = 0x3f3f3f3f;

const ll LINF = 0x3f3f3f3f3f3f3f3f;

int n, m, s, t;

int len;

struct road

{

	int u, v, len, cost;

	int next;

};

struct node

{

    int v;

    int len;

    int cost;

    node(int v, int l, int c):v(v),len(l),cost(c){}

    friend bool operator <(node a, node b)

    {

        return a.len>b.len;

    }

};

road G[maxn*5];

int h[maxn];

int mx = -INF;

int d[maxn];

int c[maxn];

int path[maxn];

void dij()

{

    fill(d, d+n+1, INF);

    fill(path, path+n+1, -1);

    fill(c, c+n+1, 0);

    d[1] = 0;

    priority_queue<node> pque;

    pque.push(node(1, 0, 0));

    while(pque.size())

    {

        node p = pque.top(); pque.pop();

        int v = p.v;

        if(d[v] < p.len) continue;

        for(int i = h[v]; i != -1; i = G[i].next)

        {

            road e = G[i];

            if(d[e.v] > d[e.u] + e.len)

            {

                d[e.v] = d[e.u] + e.len;

                c[e.v] = c[e.u] + e.cost;

                path[e.v] = i;

                pque.push(node(e.v, d[e.v], c[e.v]));

            }

            else if(d[e.v] == d[e.u] + e.len)

            {

                if(path[e.v] != -1 && G[path[e.v]].cost > e.cost)

                {

                    path[e.v] = i;

                    pque.push(node(e.v, d[e.v], c[e.v]));

                }

            }

        }

    }

}

int main()

{

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

    while(~sdd(n, m) && (n||m))

    {

        int ta, tb, tc, td;

        int len = 0;

        fill(h, h+n+1, -1);

        for(int i = 0; i < m; i++)

        {

            sdddd(ta, tb, tc, td);

            G[len].u = ta;

            G[len].v = tb;

            G[len].len = tc;

            G[len].cost = td;

            G[len].next = h[ta];

            h[ta] = len++;



            G[len].u = tb;

            G[len].v = ta;

            G[len].len = tc;

            G[len].cost = td;

            G[len].next = h[tb];

            h[tb] = len++;

        }

        dij();

        int ans = 0;

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

        {

            if(path[i]!=-1)

            {

                ans += G[path[i]].cost;

            }

        }

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

    }



	return 0;

}