#include<iostream>

#include<cstring>

#include<cstdlib>

#include<cstdio>

#include<algorithm>

#define ll long long

using namespace std;

const int maxn=;

const ll inf=1e15;

struct poi{ll sum, delta;}tree[maxn<<];

struct tjm{int too, pre;}e[maxn<<], e2[maxn<<], e3[maxn<<];

struct qaq{int x, y, cost, pos;}q[maxn];

ll dp[maxn];

int n, m, x, y, tot, tot2, tot3, tott, l[maxn], r[maxn], last[maxn], last2[maxn], last3[maxn];

inline void read(int &k)

{

    int f=; k=; char c=getchar();

    while(c<'' || c>'') c=='-' && (f=-), c=getchar();

    while(c<='' && c>='') k=k*+c-'', c=getchar();

    k*=f;

}

inline void add(int x, int y){e[++tot]=(tjm){y, last[x]}; last[x]=tot;}

inline void add2(int x, int y){e2[++tot2]=(tjm){y, last2[x]}; last2[x]=tot2;}

inline void add3(int x, int y){e3[++tot3]=(tjm){y, last3[x]}; last3[x]=tot3;}

inline void up(int x) {tree[x].sum=min(tree[x<<].sum, tree[x<<|].sum);}

inline void addone(int x, int l, int r, ll delta)

{

    tree[x].delta=min(inf, tree[x].delta+delta);

    tree[x].sum=min(inf, tree[x].sum+delta);

}

inline void down(int x, int l, int r)

{

    int mid=(l+r)>>;

    addone(x<<, l, mid, tree[x].delta);

    addone(x<<|, mid+, r, tree[x].delta);

    tree[x].delta=;

}

void build(int x, int l, int r)

{

    if(l==r) {tree[x].sum=inf; return;}

    int mid=(l+r)>>;

    build(x<<, l, mid); build(x<<|, mid+, r);

    up(x);

}

void update(int x, int l, int r, int cx, ll delta)

{

    if(l==r) {tree[x].sum=delta; return;}

    down(x, l, r);

    int mid=(l+r)>>;

    if(cx<=mid) update(x<<, l, mid, cx, delta);

    else update(x<<|, mid+, r, cx, delta);

    up(x);

}

void change(int x, int l, int r, int cl, int cr, ll delta)

{

    if(cl>cr) return;

    if(cl<=l && r<=cr) {addone(x, l, r, delta); return;}

    down(x, l, r);

    int mid=(l+r)>>;

    if(cl<=mid) change(x<<, l, mid, cl, cr, delta);

    if(cr>mid) change(x<<|, mid+, r, cl, cr, delta);

    up(x);

}

ll query(int x, int l, int r, int cl, int cr)

{

    if(cl>cr) return inf;

    if(cl<=l && r<=cr) return tree[x].sum;

    down(x, l, r);

    int mid=(l+r)>>; ll ans=inf;

    if(cl<=mid) ans=query(x<<, l, mid, cl, cr);

    if(cr>mid) ans=min(ans, query(x<<|, mid+, r, cl, cr));

    return ans;

}

void dfs1(int x, int fa)

{

    l[x]=++tott;

    for(int i=last[x], too;i;i=e[i].pre)

    if((too=e[i].too)!=fa) dfs1(too, x);

    r[x]=tott;

}

inline int find(int x)

{

    int l=, r=m+;

    while(l<r)

    {

        int mid=(l+r)>>;

        if(q[mid].pos>=x) r=mid;

        else l=mid+;

    }

    return l;

}

void dfs2(int x, int fa)

{

    ll sum=;

    for(int i=last[x], too;i;i=e[i].pre)

    if((too=e[i].too)!=fa) dfs2(too, x), sum=min(inf, sum+dp[too]);

    if(x==) {dp[]=sum; return;}

    for(int i=last2[x];i;i=e2[i].pre) update(, , m, e2[i].too, min(inf, q[e2[i].too].cost+sum));

    for(int i=last3[x];i;i=e3[i].pre) update(, , m, e3[i].too, inf);

    for(int i=last[x], too;i;i=e[i].pre)

    if((too=e[i].too)!=fa) change(, , m, find(l[too]), find(r[too]+)-, sum-dp[too]);

    dp[x]=query(, , m, find(l[x]), find(r[x]+)-);

}

inline bool cmp(qaq a, qaq b){return a.pos<b.pos;}

int main()

{

    read(n); read(m); build(, , m);

    for(int i=;i<n;i++) read(x), read(y), add(x, y), add(y, x);

    dfs1(, );

    for(int i=;i<=m;i++) read(q[i].x), read(q[i].y), read(q[i].cost), q[i].pos=l[q[i].x];

    sort(q+, q++m, cmp); q[m+].pos=n+;

    for(int i=;i<=m;i++) add2(q[i].x, i), add3(q[i].y, i);

    dfs2(, );

    if(dp[]>=inf) return puts("-1"), ;

    printf("%lld\n", dp[]);

}