#include<stdio.h>#include<string.h>#define MAXD 110#define MAXM 20100const long long int INF = 10000000000000000ll;int first[MAXD], next[MAXM], v[MAXM], a[MAXM], b[MAXM], N, M, e;int p[MAXD], link[MAXD], q[MAXD], inq[MAXD];long long int w[MAXM], cost[MAXM], flow[MAXM], D, K;long long int d[MAXD];void add(int x, int y, long long int c, long long int f){    v[e] = y;    cost[e] = c;    flow[e] = f;    next[e] = first[x];    first[x] = e;    e ++;}int init(){int i;if(scanf("%d%d", &N, &M) != 2)return 0;for(i = 0; i < M; i ++)        scanf("%d%d%lld", &a[i], &b[i], &w[i]);    scanf("%lld%lld", &D, &K);    e = 0;    memset(first, -1, sizeof(first));for(i = 0; i < M; i ++)    {        add(a[i], b[i], w[i], K);        add(b[i], a[i], -w[i], 0);        add(b[i], a[i], w[i], K);        add(a[i], b[i], -w[i], 0);    }    add(0, 1, 0, D);    add(1, 0, 0, 0);return 1;}void SPFA(){int i, u, front, rear;for(i = 1; i <= N; i ++)        d[i] = INF;    d[0] = 0;    memset(inq, 0, sizeof(inq));    front = rear = 0;    q[rear ++] = 0;    inq[0] = 1;while(front != rear)    {        u = q[front ++];if(front > N)            front = 0;        inq[u] = 0;for(i = first[u]; i != -1; i = next[i])if(flow[i] && d[u] + cost[i] < d[v[i]])            {                d[v[i]] = d[u] + cost[i];                p[v[i]] = u;                link[v[i]] = i;if(!inq[v[i]])                {                    q[rear ++] = v[i];if(rear > N)                        rear = 0;                    inq[v[i]] = 1;                }            }    }}long long int mincost(){long long int res = 0, f = 0, a;int i, u;for(;;)    {        SPFA();if(d[N] == INF)break;        a = INF;for(u = N; u != 0; u = p[u])        {int y =link[u];if(flow[y] < a)                a = flow[y];        }for(u = N; u != 0; u = p[u])        {int y = link[u];            flow[y] -= a;            flow[y ^ 1] += a;        }        res += a * d[N];        f += a;    }if(f == D)return res;elsereturn -1;}int main(){while(init())    {long long int res = mincost();if(res >= 0)            printf("%lld\n", res);else            printf("Impossible.\n");    }return 0;}