#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#include "bits/stdc++.h"

using namespace std;
using ll = long long int;

#define debug(v) {printf("L%d %s > ",__LINE__,#v);cout<<(v)<<endl;}
#define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:(v)){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) {printf("L%d %s > ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;}
#define debugaa(m,h,w) {printf("L%d %s >\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}}
#define ALL(v) (v).begin(),(v).end()
#define repeat(cnt,l) for(remove_const<decltype(l)>::type cnt=0;(cnt)<(l);++(cnt))
#define rrepeat(cnt,l) for(auto cnt=(l)-1;0<=(cnt);--(cnt))
#define iterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);++(cnt))
#define diterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);--(cnt))
const ll MD = 1000000007ll; const long double PI = 3.1415926535897932384626433832795L;
template<typename T1, typename T2> inline void assert_equal(T1 expected, T2 actual) { if (!(expected == actual)) { cerr << "assertion fault: expected=" << expected << " actual=" << actual << endl; abort(); } }
template<typename T1, typename T2> inline void assert_less(T1 actual, T2 threshold) { if (!(actual < threshold)) { cerr << "assertion fault: " << actual << " < (const)" << threshold << endl; abort(); } }
template<typename T1, typename T2> inline void assert_eqless(T1 actual, T2 threshold) { if (!(actual <= threshold)) { cerr << "assertion fault: " << actual << " <= (const)" << threshold << endl; abort(); } }
template<typename T1, typename T2> inline ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << '(' << p.first << ':' << p.second << ')'; return o; }
template<typename Vec> inline ostream& _ostream_vecprint(ostream &o, const Vec& p) { o << '['; for (auto& e : p) o << e << ','; o << ']'; return o; }
template<typename T> inline ostream& operator<<(ostream& o, const vector<T>& v) { return _ostream_vecprint(o, v); }
template<typename T, size_t S> inline ostream& operator<<(ostream& o, const array<T, S>& v) { return _ostream_vecprint(o, v); }
template<typename T> inline T& maxset(T& to, const T& val) { return to = max(to, val); }
template<typename T> inline T& minset(T& to, const T& val) { return to = min(to, val); }
void bye(string s, int code = 0) { cout << s << endl; exit(code); }
mt19937_64 randdev(8901016);
template<typename T> inline T rand(T l, T h) { return uniform_int_distribution<T>(l, h)(randdev); }
template<> inline double rand<double>(double l, double h) { return uniform_real_distribution<double>(l, h)(randdev); }
template<> inline float rand<float>(float l, float h) { return uniform_real_distribution<float>(l, h)(randdev); }

#if defined(_WIN32) || defined(_WIN64)
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#elif defined(__GNUC__)
#else
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
namespace {
#define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E)
    class MaiScanner {
    public:
        template<typename T> void input_integer(T& var) {
            var = 0; T sign = 1;
            int cc = getchar_unlocked();
            for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc && cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var * sign;
        }
        inline int c() { return getchar_unlocked(); }
        inline MaiScanner& operator>>(int& var) { input_integer<int>(var); return *this; }
        inline MaiScanner& operator>>(long long& var) { input_integer<long long>(var); return *this; }
        inline MaiScanner& operator>>(string& var) {
            int cc = getchar_unlocked();
            for (; !isvisiblechar(cc); cc = getchar_unlocked());
            for (; isvisiblechar(cc); cc = getchar_unlocked())
                var.push_back(cc);
            return *this;
        }
        template<typename IT> void in(IT begin, IT end) { for (auto it = begin; it != end; ++it) *this >> *it; }
    };
    class MaiPrinter {
    public:
        template<typename T>
        void output_integer(T var) {
            if (var == 0) { putchar_unlocked('0'); return; }
            if (var < 0)
                putchar_unlocked('-'),
                var = -var;
            char stack[32]; int stack_p = 0;
            while (var)
                stack[stack_p++] = '0' + (var % 10),
                var /= 10;
            while (stack_p)
                putchar_unlocked(stack[--stack_p]);
        }
        inline MaiPrinter& operator<<(char c) { putchar_unlocked(c); return *this; }
        inline MaiPrinter& operator<<(int var) { output_integer<int>(var); return *this; }
        inline MaiPrinter& operator<<(long long var) { output_integer<long long>(var); return *this; }
        inline MaiPrinter& operator<<(char* str_p) { while (*str_p) putchar_unlocked(*(str_p++)); return *this; }
        inline MaiPrinter& operator<<(const string& str) {
            const char* p = str.c_str();
            const char* l = p + str.size();
            while (p < l) putchar_unlocked(*p++);
            return *this;
        }
        template<typename IT> void join(IT begin, IT end, char sep = '\n') { for (auto it = begin; it != end; ++it) *this << *it << sep; }
    };
}
MaiScanner scanner;
MaiPrinter printer;


class GraphE {
public:
    typedef int W_T;
    struct Edge {
        int u, v;
        W_T value;
        Edge(int from = 0, int to = 0, W_T value = 0) :u(from), v(to), value(value) {}
        inline int to(int _v) const { return _v == v ? u : v; }
    };
    size_t n;
    vector<vector<int>> vertex_to;
    vector<Edge> edges;

    GraphE(int n = 1) :n(n), vertex_to(n) { }

    void resize(size_t _n) {
        n = _n;
        vertex_to.resize(_n);
    }
    void connect(int from, int to, W_T val = 0) {
        vertex_to[(size_t)from].push_back((int)edges.size());
        vertex_to[(size_t)to].push_back((int)edges.size());
        edges.emplace_back(from, to, val);
    }
};


//ll dp[101][101];

void solve(int N, int M, int L) {

    GraphE graph(N);
    vector<pair<int, ll>> edgeval; // dist,nOfEnemy
    edgeval.reserve(M);

    repeat(i, M) {
        int a, b, d, e;
        scanner >> a >> b >> d >> e;
        --a; --b;
        graph.connect(a, b);
        edgeval.emplace_back(d, ll(e));
    }

    //fill(dp[0], dp[101], ll(1e18));
    vector<vector<ll>> dp(101);
    repeat(i, N) dp[i].resize(L + 1, ll(1e18));

    priority_queue<tuple<ll,ll,int>> pq;
    dp[0][L] = 0;
    pq.emplace(0,L,0);

    ll best = 1e18;

    while (!pq.empty()) {
        ll enemy,money;
        int idx;
        tie(enemy,money,idx) = pq.top(); pq.pop();
        enemy = -enemy;

        if (idx == N - 1) {
            minset(best, enemy);
            continue;
        }

        if (enemy > dp[idx][money]) continue;
        
        for (int ei : graph.vertex_to[idx]) {
            int d; ll e; int to;
            tie(d, e) = edgeval[ei];
            to = graph.edges[ei].to(idx);
            if (money >= d && dp[to][money-d] > enemy) {
                dp[to][money-d] = enemy;
                pq.emplace(-(enemy), money - d, to);
            }
            if (dp[to][money] > enemy + e) {
                dp[to][money] = enemy + e;
                pq.emplace(-(enemy + e), money, to);
            }
        }
    }
    assert(best < ll(1e18));
    printer << best << '\n';
}


int main() {

    int n, m, l;
    while (scanner >> n >> m >> l, n != 0 || m != 0 || l != 0) {
        solve(n, m, l);
    }

    return 0;
}



Measured memory_bytes: 4196