#include <queue>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>using namespace std;#define INF 0x7ffffffstruct EdgeType {int v,e;double w;
};
struct EdgeType edge[800005];struct PointType {int x,y;
};
struct PointType node[205];int n,m,head[205],cnt=1,pre[205],tot,uu[2005],vv[2005];double dis[205],shorest=INF,ans=INF;bool if_[205];inline void in(int &now)
{int if_z=1;now=0;char Cget=getchar();while(Cget>'9'||Cget<'0'){if(Cget=='-') if_z=-1;Cget=getchar();}while(Cget>='0'&&Cget<='9'){now=now*10+Cget-'0';Cget=getchar();}now*=if_z;
}inline double d(int u,int v)
{double xx=node[u].x-node[v].x;double yy=node[u].y-node[v].y;return sqrt(xx*xx+yy*yy);
}inline void edge_add(int u,int v,double w)
{edge[++cnt].e=head[u],head[u]=cnt,edge[cnt].v=v,edge[cnt].w=w;edge[++cnt].e=head[v],head[v]=cnt,edge[cnt].v=u,edge[cnt].w=w;
}void spfa(int pu,int pv)
{for(int i=1;i<=n;i++) dis[i]=INF,if_[i]=false,pre[i]=-1;queue<int>que;que.push(1),dis[1]=0,if_[1]=true;while(!que.empty()){int now=que.front();que.pop(),if_[now]=false;for(int i=head[now];i;i=edge[i].e){if((now==pu&&edge[i].v==pv)||(now==pv&&edge[i].v==pu)) continue;if(dis[edge[i].v]>dis[now]+edge[i].w){pre[edge[i].v]=i;dis[edge[i].v]=dis[now]+edge[i].w;if(!if_[edge[i].v]){que.push(edge[i].v);if_[edge[i].v]=true;}}}}
}int main()
{in(n),in(m);int u,v;for(int i=1;i<=n;i++) in(node[i].x),in(node[i].y);for(int i=1;i<=m;i++){in(u),in(v);edge_add(u,v,d(u,v));}spfa(0,0),shorest=dis[n];if(shorest==INF){printf("-1");return 0;}int now=n;while(pre[now]!=-1){tot++;vv[tot]=edge[pre[now]].v;uu[tot]=edge[pre[now]^1].v;now=edge[pre[now]^1].v;}for(int i=1;i<=tot;i++){spfa(uu[i],vv[i]);ans=min(ans,dis[n]);}if(ans!=INF) printf("%.2f\n",ans);else printf("-1\n");return 0;
}