#define _CRT_SECURE_NO_WARNINGS
//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
#define all(c) (c).begin(), (c).end()
#define loop(i,a,b) for(ll i=a; i<ll(b); i++)
#define rep(i,b) loop(i,0,b)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
template<class T> istream& operator>>(istream& is, vector<T>& v);
template<class T> ostream& operator<<(ostream& os, vector<T> const& v);
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream&, const tuple<T...>&){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream& os, const tuple<T...>& t){ os << (n==0?"":" ") << get<n>(t); _ot<n+1>(os, t); }
template<class...T> ostream& operator<<(ostream& os, const tuple<T...>& t){ _ot<0>(os, t); return os; }
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _it(istream&, tuple<T...>&){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _it(istream& is, tuple<T...>& t){ is >> get<n>(t); _it<n+1>(is, t); }
template<class...T> istream& operator>>(istream& is, tuple<T...>& t){ _it<0>(is, t); return is; }
template<class T> istream& operator>>(istream& is, vector<T>& v){ rep(i,v.size()) is >> v[i]; return is; }
template<class T> ostream& operator<<(ostream& os, vector<T> const& v){ rep(i,v.size()) os << v[i] << (i+1==(int)v.size()?"":" "); return os; }
#ifdef DEBUG
#define dump(...) (cerr<<#__VA_ARGS__<<" = "<<mt(__VA_ARGS__)<<" ["<<__LINE__<<"]"<<endl)
#else
#define dump(...)
#endif


// グラフ用ヘッダ

struct Edge {
    int src, dst;
    int weight, money;
    Edge(int src, int dst, int weight, int money) :
        src(src), dst(dst), weight(weight), money(money) { }
};
bool operator < (const Edge &e, const Edge &f) {
    return e.weight != f.weight ? e.weight > f.weight : // !!INVERSE!!
        e.src != f.src ? e.src < f.src : e.dst < f.dst;
}
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

typedef tuple<int,int,int> State;
int dp[111][111];

ll encode(ll a, ll b, ll c){
    return a<<32 | b<<16 | c;
}

tuple<int,int,int> decode(ll x){
    return mt(x>>32, x>>16 & 0xFFFF, x & 0xFFFF);
}

int main(){
    int N,M,L;
    while(cin>>N>>M>>L && N){
        Graph g(N);
        rep(i,M){
            int a,b,d,e;
            cin>>a>>b>>d>>e; a--; b--;
            swap(d,e);
            g[a].eb(a,b,d,e);
            g[b].eb(b,a,d,e);
        }
        rep(i,111)rep(j,111) dp[i][j] = 1<<29;
        dp[0][L] = 0;
        priority_queue<ll> q;
        q.emplace(encode(0,0,L));
        while(q.size()){
            int c,v,money;
            tie(c,v,money) = decode(q.top()); q.pop();
            c = -c;
            if(dp[v][money] < c) continue;
            for(auto & e : g[v]){
                if(dp[v][money] + e.weight < dp[e.dst][money]){
                    dp[e.dst][money] = dp[v][money] + e.weight;
                    q.emplace(encode(-dp[v][money]+e.weight, e.dst, money));
                }
                if(money >= e.money && dp[v][money] < dp[e.dst][money-e.money]){
                    dp[e.dst][money-e.money] = dp[v][money];
                    q.emplace(encode(-dp[v][money], e.dst, money-e.money));
                }
            }
        }
        int ans = dp[N-1][0];
        rep(i,111) ans = min(ans, dp[N-1][i]);
        cout << ans << endl;
    }
}

Measured memory_bytes: 1800