#include<bits/stdc++.h>
using namespace std;

const int N=1e5+1e3+7,M=1e6+1e3+7;

int cnt=1,head[N],hd[N];

struct Edge{
    int ne,to,w;
}edg[M*2+1];

int n , m ,p , s , t;
int build(int u,int v,int w)
{
    ++cnt;
    edg[cnt].to=v;
    edg[cnt].ne=head[u];
    edg[cnt].w=w;
    head[u]=cnt;
    ++cnt;
    edg[cnt].to=u;
    edg[cnt].ne=head[v];
    edg[cnt].w=0;
    head[v]=cnt;
    return cnt^1;
}

int d[N];

int S,T;//S=0, T=n+1

queue<int> q;

bool bfs()
{
    fill(d+1,d+n+1,-1);
    d[S]=0;
    q.push(S);
    while(!q.empty())
    {
        int x=q.front();
        q.pop();
        hd[x]=head[x];
        for(int tmp=head[x];tmp;tmp=edg[tmp].ne)
        {
            int v=edg[tmp].to;
            if(d[v]!=-1||!edg[tmp].w)
                continue;
            d[v]=d[x]+1;
            q.push(v);
        }
    }
    return d[T]!=-1;
}

int dinic(int x,int mn)
{
    if(x==T||!mn)
        return mn;
    int flow=0,tmpf;
    for(int &tmp=hd[x];tmp;tmp=edg[tmp].ne)
    {
        int v=edg[tmp].to;
        if(d[v]==d[x]+1&&(tmpf=dinic(v,min(mn,edg[tmp].w)))>0)
        {
            flow+=tmpf;
            mn-=tmpf;
            edg[tmp].w-=tmpf;
            edg[tmp^1].w+=tmpf;
        }
        if(!mn)
            break;
    }
    return flow;
}

int flow()
{
    int ret=0;
    while(bfs())
        ret+=dinic(S,INT_MAX);
    return ret;
}

typedef pair<int,int> pii;
struct {
    int dis[205];
    Edge edg[M * 2 + 1] ;
    int head[N];
    int cnt;

    int adde(int u,int v,int w) {
        ++cnt;
        edg[cnt].to=v;
        edg[cnt].ne=head[u];
        edg[cnt].w=w;
        head[u]=cnt;
        return cnt;
    }
    void dij(int s) {
        for(int i = 1;i <= n;i++) dis[i] = 1e9;
        dis[s] = 0;
        priority_queue<pii , vector<pii> , greater<pii> > pq;
        pq.push({0 , s});
        while(pq.size()) {
            auto [w,u] = pq.top() ; pq.pop() ;
            // printf("dis %d %d\n",u,w);
            if(w != dis[u]) continue ;
            // printf("%d %d\n",u,hd[u]);
            // printf("dis %d %d\n",u,w);
            for(int tmp=head[u];tmp;tmp=edg[tmp].ne) {
                int v=edg[tmp].to;
                // printf("edge %d %d : %d\n",u,v,edg[tmp].w);
                if(dis[v] > dis[u] + edg[tmp].w) {
                    dis[v] = dis[u] + edg[tmp].w;
                // printf("upd %d %d %d %d\n",u,v,dis[u],edg[tmp].w);
                    pq.push({dis[v] , v});
                }
            }
        }
        return ;
    }
}D;
const int inf = 1e9;
int dd[2005] , c[2005];
pii E[2005];
bool in[2005];
int main()
{
    ios::sync_with_stdio(false) ; cin.tie(0);
    cin >> n >> m >> p >> s >> t;
    S = s ; T = t;
    for(int i = 1;i <= m;i++) {
        int u , v ;cin >> u >> v >> dd[i] >> c[i];
        // build(u , v , w);
        D.adde(u , v , dd[i]);
        in[i] = 0;
        E[i] = {u , v};
    }
    int cost = 0;
    D.dij(s) ;
    double ans = D.dis[t];
    int cur = 0;
    while(cost < p) {
        D.dij(s) ;
        // printf("ok %d %d\n" , cost , p); exit(0) ;
        // printf("%d %d\n" , D.dis[t] , cost);
        int cdis = D.dis[t];
        for(int i = 1 ; i <= m;i++) {
            if(in[i]) continue ;
            auto [u,v] = E[i];
            if(D.dis[v] == D.dis[u] + dd[i]) {
                // printf("adde %d %d %d\n",u,v,c[i]);
                build(u , v , c[i]);
                in[i] = 1;
            }
            //build()
        }
        cur += flow();
        bfs() ;
        // for(int i = 1;i <= n;i++) printf("D %d %d\n",i,d[i]);
        for(int i = 1;i <= m;i++) {
            auto [u,v] = E[i] ;
            if((d[u] != -1 && d[v] == -1) && in[i]) {
                // printf("cut %d %d\n",u,v);
                D.edg[i].w = inf;
            }
            else D.edg[i].w = dd[i] ;
        }
        D.dij(s) ;
        int upper = D.dis[t];
        // printf("upper %d %d\n",upper , cdis) ;
        if(cost + 1LL * cur * (upper - cdis) < p) {
            cost += cur * (upper - cdis) ; ///every add upper - cdis
            ans += (upper - cdis);
            for(int i = 1;i <= m;i++) {
                auto [u,v] = E[i];
                if((d[u] != -1 && d[v] == -1) && in[i]) {
                    dd[i] += (upper - cdis) ;
                }
            }
            continue ;
        }
        else {ans += (double)(p - cost) / cur ; break;}
        // exit(0);
    }
    printf("%.12lf\n" ,ans);
}