#include <bits/stdc++.h>
#define int long long
#define INF2 100000000000000ll
#define INF 0x3f3f3f3f3f3f3f3f
#define f(x,y) ((x)*2+(y))
int S,T,N,M,a[509],c[509],b[509],hd[1009],to[100009],nxt[100009],val[100009],k=1,
d[1009],cur[1009];
inline bool bfs(void) {
    std::queue<int> Q;
    Q.push(S);
    bool v[1009];
    memset(v,0,sizeof(v));
    v[S]=1;
    while(!Q.empty()) {
        int n=Q.front();Q.pop();
        for(int i=hd[n];i;i=nxt[i])
            if(!v[to[i]]&&val[i])
                v[to[i]]=1,Q.push(to[i]),d[to[i]]=d[n]+1;
    }
    return v[T];
}
inline int dfs(int nod,int v) {
    if((nod==T)||(v==0)) return v;
    int flow=0,f;
    for(int& i=cur[nod];i;i=nxt[i])
        if(d[nod]+1==d[to[i]]&&(f=dfs(to[i],std::min(v,val[i])))) {
            val[i]-=f;val[i^1]+=f;flow+=f;v-=f;
            if(v==0) break;
        }
    if(!flow) d[nod]=-1;
    return flow;
}
inline void set(void) {for(int i=1;i<=T;i++) cur[i]=hd[i];}
void l(int u,int v,int w) {
    to[++k]=v;nxt[k]=hd[u];val[k]=w;hd[u]=k;
}
void co(int u,int v,int w) {
    l(u,v,w),l(v,u,0);
}
signed main(void) {
    scanf("%lld %lld",&N,&M);
    S=1;T=2*N+2;
    for(int i=1;i<N;i++) {
        scanf("%lld",&a[i]);
    }
    for(int i=1;i<=N;i++) {
        scanf("%lld",&c[i]);
    }
    for(int i=1;i<N;i++) {
        scanf("%lld",&b[i]);
    }
    if(N==1) {
        printf("%lld",c[1]);
        return 0;
    }
    b[1]+=c[1];
    a[N-1]+=c[N];
    for(int i=1;i<N;i++) {
        co(S,f(i,0),b[i]+INF2);
        co(f(i,1),T,a[i]+INF2);
        co(f(i,0),f(i,1),INF);
    }
    while(M--) {
        int x,y,c;
        scanf("%lld %lld %lld",&x,&y,&c);
        co(f(x,0),f(y,1),c);
    }
    for(int i=1;i+1<N;i++) {
        co(f(i,0),f(i+1,1),c[i+1]);
        co(f(i,1),f(i+1,0),c[i+1]);
    }
    int ans=0;
    while(bfs()) {
        set();
        ans+=dfs(S,INF);
    }
    printf("%lld",ans-INF2*(N-1));
}