#include<bits/stdc++.h>

using namespace std;

#define il inline

#define lf double

#define gc getchar()

#define t(i) edge[i].to

#define ri register int

#define rc register char

#define rb register bool

#define rp(i,x,y) for(ri i=x;i<=y;++i)

#define my(i,x,y) for(ri i=x;i>=y;--i)

#define e(i,x) for(ri i=head[x];i;i=edge[i].nxt)

const int N=+,inf=1e9;

const lf eps=1e-;

int n,K,sz[N];

lf f[N][N],q[N],tmp[N];

vector<int>V[N];

struct node{int s,p;}nod[N];

il int read()

{

    rc ch=gc;ri x=;rb y=;

    while(ch!='-' && (ch>'' || ch<''))ch=gc;

    if(ch=='-')ch=gc,y=;

    while(ch>='' && ch<='')x=(x<<)+(x<<)+(ch^''),ch=gc;

    return y?x:-x;

}

il void merg(ri x,ri y)

{

    rp(i,,K)tmp[i]=-inf;

    rp(i,,sz[x])rp(j,,min(K-i,sz[y]))tmp[i+j]=max(f[x][i]+f[y][j],tmp[i+j]);

    rp(i,,K)f[x][i]=max(f[x][i],tmp[i]);

}

void dfs(ri nw){ri siz=V[nw].size();sz[nw]=;rp(i,,siz-)dfs(V[nw][i]),merg(nw,V[nw][i]),sz[nw]+=sz[V[nw][i]];}

il bool check(lf dat){memset(f,-,sizeof(f));rp(i,,n)f[i][]=nod[i].p-dat*nod[i].s;dfs();return f[][K]>=;}

int main()

{

    freopen("4322.in","r",stdin);freopen("4322.out","w",stdout);

    K=read()+;n=read();rp(i,,n){nod[i]=(node){read(),read()};V[read()].push_back(i);}

    lf l=,r=;while(r-l>=eps){lf mid=(l+r)/;if(check(mid))l=mid;else r=mid;}printf("%.3lf\n",r);

    return ;

}