// 私は猫です

#include<bits/stdc++.h>
#define ull unsigned long long
#define ll long long
#define pb push_back
#define mkp make_pair
#define fi first
#define se second
#define inf 1000000000
#define infll 1000000000000000000ll
#define pii pair<int,int>
#define rep(i,a,b,c) for(int i=(a);i<=(b);i+=(c))
#define per(i,a,b,c) for(int i=(a);i>=(b);i-=(c))
#define F(i,a,b) for(int i=a,i##end=b;i<=i##end;i++)
#define dF(i,a,b) for(int i=a,i##end=b;i>=i##end;i--)
#define cmh(sjy) while(sjy--)
#define lowbit(x) ((x)&(-(x)))
#define HH printf("\n")
#define eb emplace_back
#define poly vector<int>
#define SZ(x) ((int)x.size())
using namespace std;
template<typename T>inline void chkmax(T &x,const T &y){ x=std::max(x,y); }
template<typename T>inline void chkmin(T &x,const T &y){ x=std::min(x,y); }
const int mod=998244353,maxn=500005;
vector<array<ll,3>>g[maxn];
int dis[maxn],cur[maxn],q[maxn],N,S,T,id[maxn],n,zsy;
ll co[maxn][2];
void add(int u,int v,ll w){ g[u].push_back({v,w,SZ(g[v])}),g[v].push_back({u,0,SZ(g[u])-1}); }
bool bfs(){
	F(i,0,N)cur[i]=dis[i]=0;
	int qL=1,qR=0; dis[q[++qR]=S]=1;
	while(qL<=qR){
		const int u=q[qL++];
		for(auto [v,w,e]:g[u])if(w&&!dis[v]){
			dis[v]=dis[u]+1,q[++qR]=v;
			if(v==T)return 1;
		}
	} return 0;
}
ll dfs(int u,ll f){
	if(u==T)return f;
	ll res=0;
	for(int &i=cur[u];i<SZ(g[u]);++i){
		const int v=g[u][i][0]; ll &w=g[u][i][1];
		if(w&&dis[v]==dis[u]+1){
			ll val=dfs(v,min(f,w));
			w-=val,g[v][g[u][i][2]][1]+=val;
			f-=val,res+=val;
			if(!f)return res;
		}
	}
	return res;
}
void solve(){
	cin>>n>>zsy,S=++N,T=++N;
	if(n==1){
		int x; cin>>x;
		cout<<x<<'\n';
		return;
	}
	F(i,1,n-1)id[i]=++N;
	F(i,1,n-1){ int x; cin>>x,co[i][0]+=x; }
	F(i,1,n){
		int x; cin>>x;
		if(i==1)co[1][1]+=x;
		else if(i==n)co[n-1][0]+=x;
		else add(id[i],id[i-1],x),add(id[i-1],id[i],x);
	}
	F(i,1,n-1){ int x; cin>>x,co[i][1]+=x; }
	F(i,1,n-1)add(S,id[i],co[i][0]);
	F(i,1,n-1)add(id[i],T,co[i][1]);
	F(_,1,zsy){ int x,y,c; cin>>x>>y>>c,add(id[x],id[y],c); }
	ll ans=0;
	while(bfs())ans+=dfs(S,infll);
	cout<<ans;
}
signed main(){
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int zsy=1;
	F(____,1,zsy)solve();
}