#include<iostream>
#include<cstring>
#include<cstdlib>
#include<cstdio>
#include<algorithm>
#define ll long long
using namespace std;
const int maxn=500010;
const ll inf=1e15;
struct poi{ll sum, delta;}tree[maxn<<2];
struct tjm{int too, pre;}e[maxn<<1], e2[maxn<<1], e3[maxn<<1];
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=1; k=0; char c=getchar();while(c<'0' || c>'9') c=='-' && (f=-1), c=getchar();while(c<='9' && c>='0') k=k*10+c-'0', 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<<1].sum, tree[x<<1|1].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)>>1;addone(x<<1, l, mid, tree[x].delta);addone(x<<1|1, mid+1, r, tree[x].delta);tree[x].delta=0;
}
void build(int x, int l, int r)
{if(l==r) {tree[x].sum=inf; return;}int mid=(l+r)>>1;build(x<<1, l, mid); build(x<<1|1, mid+1, 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)>>1;if(cx<=mid) update(x<<1, l, mid, cx, delta);else update(x<<1|1, mid+1, 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)>>1;if(cl<=mid) change(x<<1, l, mid, cl, cr, delta);if(cr>mid) change(x<<1|1, mid+1, 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)>>1; ll ans=inf;if(cl<=mid) ans=query(x<<1, l, mid, cl, cr);if(cr>mid) ans=min(ans, query(x<<1|1, mid+1, 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=1, r=m+1;while(l<r){int mid=(l+r)>>1;if(q[mid].pos>=x) r=mid;else l=mid+1; }return l;
}
void dfs2(int x, int fa)
{ll sum=0;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==1) {dp[1]=sum; return;}for(int i=last2[x];i;i=e2[i].pre) update(1, 1, m, e2[i].too, min(inf, q[e2[i].too].cost+sum));for(int i=last3[x];i;i=e3[i].pre) update(1, 1, m, e3[i].too, inf);for(int i=last[x], too;i;i=e[i].pre)if((too=e[i].too)!=fa) change(1, 1, m, find(l[too]), find(r[too]+1)-1, sum-dp[too]);dp[x]=query(1, 1, m, find(l[x]), find(r[x]+1)-1);
}
inline bool cmp(qaq a, qaq b){return a.pos<b.pos;}
int main()
{read(n); read(m); build(1, 1, m);for(int i=1;i<n;i++) read(x), read(y), add(x, y), add(y, x);dfs1(1, 0); for(int i=1;i<=m;i++) read(q[i].x), read(q[i].y), read(q[i].cost), q[i].pos=l[q[i].x];sort(q+1, q+1+m, cmp); q[m+1].pos=n+1;for(int i=1;i<=m;i++) add2(q[i].x, i), add3(q[i].y, i);dfs2(1, 0);if(dp[1]>=inf) return puts("-1"), 0;printf("%lld\n", dp[1]);
}