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| #include<bits/stdc++.h>
#define N 1010
#define sqr(a) ((a)*(a))
#define fsb(a,b,c) for(register int a=b;a<=(c);a++)
#define fbs(a,b,c) for(register int a=b;a>=(c);a--)
using namespace std;
struct node{
int x,y;
}a[N],b[N*N];
int n,m,cnt=0,fa[N];
inline double getdis(int i,int j){
return sqrt(sqr(a[i].x-a[j].x)+sqr(a[i].y-a[j].y));
}
inline int cmp(node a,node b){
return getdis(a.x,a.y)<getdis(b.x,b.y);
}
inline int getf(int x){
return x==fa[x]?x:fa[x]=getf(fa[x]);
}
template<typename qw>inline void rll(qw &x){
x=0;qw f=1;char c=getchar();
while(!isdigit(c))f=c=='-'?-1:f,c=getchar();
while(isdigit(c))x=x*10+c-'0',c=getchar();
}
int main(){
rll(n);rll(m);
fsb(i,1,n){
rll(a[i].x);rll(a[i].y);
fsb(j,1,i-1)b[++cnt]=(node){j,i};
}
sort(b+1,b+1+cnt,cmp);
fsb(i,1,n)fa[i]=i;
fsb(i,1,cnt){
int fax=getf(b[i].x),fay=getf(b[i].y);
if(fax==fay)continue;
if(n==m){
printf("%0.2lf",getdis(b[i].x,b[i].y));
return 0;
}
fa[fay]=fax;
n--;
}
return 0;
}
|