#include <bITs/stdc++.h>
using namespace std;
#define INF 0x3f3f3f3f
#define N 100010
#define ll long long
#define reg register int
//#define int long long 

char buf[1<<21], *p1=buf, *p2=buf;
#define getchar() (p1==p2&&(p2=(p1=buf)+fread(buf, 1, 1<<21, stdin)), p1==p2?EOF:*p1++)
inline int read() {
	int ans=0, f=1; char c=getchar();
	while (!isdigit(c)) {if (c=='-') f=-f; c=getchar();}
	while (isdigit(c)) {ans=(ans<<3)+(ans<<1)+(c^48); c=getchar();}
	return ans*f;
}

int n, m;
struct Edge{int From, to, a, b; double val;}e[N];

namespace force{
	bool vis[15];
	void solve() {
		int lim=1<<;m;
		double ans=0;
		for (int s=1,s2,cnt; s<lim; ++s) {
			s2=s; cnt=0;
			ll suma=0, sumb=0;
			double sum=0;
			do {++cnt; s2&amp;=s2-1;} while (s2);
			if (cnt!=n-1) goto jump;
			for (int i=1; i<=n; ++i) vis[i]=0;
			for (int i=0; i<m; ++i) if (s&(1<<i)) {
				vis[e[i+1].from]=vis[e[i+1].to]=1;
				suma+=e[i+1].a, sumb+=e[i+1].b;
			}
			sum=sqrt(suma*suma+sumb*sumb);
			if (sum<ans) goto jump;
			for (int i=1; i<=n; ++i) if (!vis[i]) goto jump;
			// cout<<"sum: "<<sum<<' '<<bitset<10>(s)<<endl;
			ans=sum;
			jump: ;
		}
		PRintf("%.6lfn", ans);
		exit(0);
	}
}

namespace task1{
	int fa[N], ans;
	inline int find(int p) {return fa[p]==p?p:fa[p]=find(fa[p]);}
	void solve() {
		int sum=0;
		for (int i=1; i<=n; ++i) fa[i]=i;
		sort(e+1, e+m+1, [](edge a, edge b){return a.a>b.a;});
		int tot=0;
		for (int i=1; i<=m&&tot<n-1; ++i) {
			int F1=find(e[i].from), f2=find(e[i].to);
			if (f1!=f2) {
				fa[f1]=f2;
				sum+=e[i].a;
				++tot;
			}
		}
		ans=abs(sum);
		sum=0;
		for (int i=1; i<=n; ++i) fa[i]=i;
		sort(e+1, e+m+1, [](edge a, edge b){return a.a<b.a;});
		tot=0;
		for (int i=1; i<=m&&tot<n-1; ++i) {
			int f1=find(e[i].from), f2=find(e[i].to);
			if (f1!=f2) {
				fa[f1]=f2;
				sum+=e[i].a;
				++tot;
			}
		}
		ans=max(ans, abs(sum));
		double tem=ans;
		printf("%.6lfn", tem);
		exit(0);
	}
}

namespace task{
	int fa[N], top;
	const double pi=acos(-1.0);
	double alpha[N];
	inline double calc(double x1, double x2, double y1, double y2) {return (x1-x2)/(y2-y1);}
	inline int find(int p) {return fa[p]==p?p:fa[p]=find(fa[p]);}
	double kruskal(double base) {
		for (int i=1; i<=n; ++i) fa[i]=i;
		for (int i=1; i<=m; ++i) e[i].val=e[i].a*cos(base)+e[i].b*sin(base);
		sort(e+1, e+m+1, [](edge a, edge b){return a.val>b.val;});
		int tot=0; ll suma=0, sumb=0;
		for (int i=1; i<=m&&tot<n-1; ++i) {
			int f1=find(e[i].from), f2=find(e[i].to);
			if (f1!=f2) {
				fa[f1]=f2;
				suma+=e[i].a, sumb+=e[i].b;
				++tot;
			}
		}
		// cout<<"sum: "<<suma<<' '<<sumb<<endl;
		return sqrt(suma*suma+sumb*sumb);
	}
	void solve() {
		alpha[++top]=90; alpha[++top]=270;
		for (int i=1; i<=m; ++i)
			for (int j=i+1; j<=m; ++j) if (e[i].a!=e[j].a && e[i].b!=e[j].b) {
				double t=atan2(e[i].a-e[j].a, e[i].b-e[j].b);
				// cout<<"t: "<<t<<endl;
				alpha[++top]=t; alpha[++top]=(t+pi);
			}
		sort(alpha+1, alpha+top+1);
		double ans=0;
		for (int i=2; i<=top; ++i) ans=max(ans, kruskal((alpha[i-1]+alpha[i])/2));
		ans=max(ans, kruskal(0));
		printf("%.6lfn", ans);
		exit(0);
	}
}

signed main()
{
	freoPEn("mst.in", "r", stdin);
	freopen("mst.out", "w", stdout);

	n=read(); m=read();
	bool itgt=1;
	for (int i=1,u,v,a,b; i<=m; ++i) {
		u=read(); v=read(); a=read(); b=read();
		e[i].from=u; e[i].to=v; e[i].a=a; e[i].b=b;
		if (b) itgt=0;
	}
	// if (itgt) task1::solve();
	// else force::solve();
	task::solve();

	return 0;
}