#include<cstdio>
#include<algorithm>
#include<queue>
#include<iostream>

using namespace std;
const int N=1e5+10;
const double eps=1e-9;

struct edge{int f,t,l;}w[N];
int n,m,head[N],next[N],tail[N],cnt;

void add(int f,int t,int l)
{
	w[++cnt]=(edge){f,t,l};
	if (!head[f]) head[f]=tail[f]=cnt;
		else tail[f]=next[tail[f]]=cnt; 
}

double dis[N];bool inque[N];

void spfa()
{
	queue<int> Q;
	for (int i=1;i<=n;i++) dis[i]=0;
	dis[1]=1;Q.push(1);
	while (!Q.empty())
	{
		int v=Q.front();Q.pop();
		inque[v]=0;
		for (int i=head[v];i;i=next[i])
			if (dis[w[i].t]+eps<dis[v]/100*w[i].l)
			{
				dis[w[i].t]=dis[v]/100*w[i].l;
				if (!inque[w[i].t]) inque[w[i].t]=1,Q.push(w[i].t);
			}
	}
}

int main()
{
	
	freopen("toura.in","r",stdin);
	freopen("toura.out","w",stdout);
	scanf("%d%d",&n,&m);
	for (int i=1,f,t,l;i<=m;i++)
	{
		scanf("%d%d%d",&f,&t,&l);
		add(f,t,l);add(t,f,l);
	}
	spfa();
	printf("%.6lf\n",100*dis[n]);
	return 0;
}