#include <cassert>#include <cctype>#include <cmath>#include <cstdio>#include <cstdlib>#include <cstring>#include <iostream>#include <sstream>#include <iomanip>#include <string>#include <vector>#include <list>#include <set>#include <map>#include <stack>#include <queue>#include <algorithm>#include <iterator>#include <utility>using namespace std;template< class T > T _abs(T n) { return (n < 0 ? -n : n); }template< class T > T _max(T a, T b) { return (!(a < b) ? a : b); }template< class T > T _min(T a, T b) { return (a < b ? a : b); }template< class T > T sq(T x) { return x * x; }#define MP(x, y) make_pair(x, y)#define SET(p) memset(p, -1, sizeof(p))#define CLR(p) memset(p, 0, sizeof(p))#define MEM(p, v) memset(p, v, sizeof(p))#define CPY(d, s) memcpy(d, s, sizeof(s))#define SZ(c) (int)c.size()#define PB(x) push_back(x)#define ff first#define ss second#define i64 long long#define ld long double#define pii pair< i64, i64 >#define psi pair< string, int >const double EPS = 1e-9;const int INF = 0x7f7f7f7f;#define mx 50090i64 dp[mx];i64 ds[mx];i64 x[mx],y[mx];vector < pii > g[mx];struct { int u,v,t; void inp() { scanf("%d %d %d",&u,&v,&t); }}d[200090];pii nd(int u, i64 w) { return pii(w,u);}int main() {int n,m,i,j,k,u,v;i64 t,w;i64 s;cin>>n>>m>>s;n++;for(i=1;i<n;i++) scanf("%I64d %I64d",&x[i],&y[i]);for(i=0;i<m;i++) d[i].inp();cin>>x[0]>>y[0]>>x[n]>>y[n];for(i=0;i<=n;i++) ds[i]=sq(x[i]-x[0])+sq(y[i]-y[0]);for(i=0;i<m;i++) { if(ds[d[i].u]>ds[d[i].v] || d[i].u==n) g[d[i].v].PB(pii(d[i].u,d[i].t)); if(ds[d[i].u]<ds[d[i].v] || d[i].v==n) g[d[i].u].PB(pii(d[i].v,d[i].t));}priority_queue < pii , vector < pii >, greater < pii > > q;MEM(dp,63);dp[0]=0;q.push(nd(0,0));while(!q.empty()) { u=q.top().second; t=q.top().first; if(u==n) break; q.pop(); if(u && sq(dp[u]*s)>=ds[u]) continue; j=g[u].size(); for(i=0;i<j;i++) { v=g[u][i].first; w=g[u][i].second+dp[u]; if(dp[v]>w) { dp[v]=w; q.push(nd(v,w)); } }}if(q.empty()) puts("Impossible");else cout<<t<<'n';return 0;}
