#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

char*mmap();

#define RD(v) int v=0;while(c=*r++-48,c>=0)v=v*10+c;
#define RDN(v) f=*r=='-'?++r,1:0;RD(v);v=f?-v:v;
#define RDL(v) long v=0;while(c=*r++-48,c>=0)v=v*10+c;

int ufb[1000];
int uf(int i){return ufb[i]>=0?ufb[i]=uf(ufb[i]):i;}

int ax[1000],ay[1000];

main(){
	char*r=mmap(0,16*1024,1,2,0,0l);
	int c,f;

	RD(n);
	for(int i=0;i<n;++i){
		ufb[i]=-1;
		int gi=i;
		RDN(x); ax[i]=x;
		RDN(y); ay[i]=y;
		for(int j=0;j<i;++j){
			int dx=ax[j]-x;
			int dy=ay[j]-y;
			if(dx*dx+dy*dy<=100){
				int gj=uf(j);
				if(gi!=gj){
					if(ufb[gi]>ufb[gj]){
						ufb[gj]+=ufb[gi];
						ufb[gi]=gj;
						gi=gj;
					}else{
						ufb[gi]+=ufb[gj];
						ufb[gj]=gi;
					}
				}
			}
		}
	}

	int m=0;
	for(int i=0;i<n;++i){
		int x=ax[i];
		int y=ay[i];
		int g=uf(i);
		for(int j=0;j<i;++j){
			if(g==uf(j)){
				int dx=ax[j]-x;
				int dy=ay[j]-y;
				if(m<dx*dx+dy*dy){
					m=dx*dx+dy*dy;
				}
			}
		}
	}
	printf("%f",n?sqrt(m)+2.:1.);
}