#include #include #include using namespace std;

int main() { ios::sync_with_stdio(false); cin.tie(0);

int N, M;
cin >> N >> M;

vector<int> P(M);
for (int i = 0; i < M; i++) {
    cin >> P[i];
}

vector<int> A(N - 1), B(N - 1), C(N - 1);
for (int i = 0; i < N - 1; i++) {
    cin >> A[i] >> B[i] >> C[i];
}

// 统计每段铁路被经过的次数
vector<int> count(N - 1, 0);
for (int i = 1; i < M; i++) {
    int start = min(P[i - 1], P[i]) - 1;
    int end = max(P[i - 1], P[i]) - 1;
    for (int j = start; j < end; j++) {
        count[j]++;
    }
}

long long total = 0;
for (int i = 0; i < N - 1; i++) {
    long long ticket_cost = (long long)count[i] * A[i];
    long long ic_cost = C[i] + (long long)count[i] * B[i];
    total += min(ticket_cost, ic_cost);
}

cout << total << endl;

return 0;

}

#include <bits/stdc++.h> using namespace std; long long cf[100000],n,m,a[100000],x,y,z,ans; int main(){ cin>>n>>m; cin>>a[1]; for(long long i=2;i<=m;i++){ cin>>a[i]; if(a[i]>a[i-1]){ cf[a[i-1]]++; cf[a[i]]--; } else { cf[a[i-1]]--; cf[a[i]]++; } } for(long long i=1;i<n;i++){ a[i]=a[i-1]+cf[i]; cin>>x>>y>>z; ans+=min(a[i]x,z+ya[i]); } cout<<ans; return 0; }

#include<bits/stdc++.h>
using namespace std;
long long cf[100001],n,m,a[100001],x,y,z,ans;
int main(){
cin>>n>>m;
cin>>a[1];
for(int i=2;i<=m;i++){
cin>>a[i];
if(a[i]>a[i-1]){
cf[a[i-1]]++;
cf[a[i]]--;
}else{
cf[a[i-1]]--;
cf[a[i]]++;
}
}
for(int i=1;i<n;i++){
a[i]=a[i-1]+cf[i];
cin>>x>>y>>z;
ans+=min(a[i]*x,z+y*a[i]);
}
cout<<ans;
return 0;

''' #include<bits/stdc++.h> using namespace std; long long cf[100001],n,m,a[100001],x,y,z,ans;

int main(){ cin>>n>>m; cin>>a[1]; for(int i=2;i<=m;i++){ cin>>a[i]; if(a[i]>a[i-1]){ cf[a[i-1]]++; cf[a[i]]--; }else{ cf[a[i-1]]--; cf[a[i]]++; } } for(int i=1;i<n;i++){ a[i]=a[i-1]+cf[i]; cin>>x>>y>>z; ans+=min(a[i]x,z+ya[i]); } cout<<ans; return 0; } '''

#include<bits/stdc++.h>
using namespace std;
long long cf[100000],n,m,x,y,z,a[100000],ans=0; 
int main(){
	cin>>n>>m;
	cin>>a[1];
	for(long long i=2;i<=m;i++){
		cin>>a[i];
		if(a[i]>a[i-1]){
			cf[a[i-1]]++;
			cf[a[i]]--;
		}else{
			cf[a[i-1]]--;
			cf[a[i]]++;
		}
	}
	for(long long i=1;i<n;i++){
		a[i]=a[i-1]+cf[i];
		cin>>x>>y>>z;
		ans+=min(a[i]*x,z+y*a[i]);
	} 
	cout<<ans;

	return 0;
}

#include <bits/stdc++.h> using namespace std; int main() { cout << "I don't know"; return 0; }

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