#pragma GCC optimize("O3")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target("avx,avx2,fma")

#include <bits/stdc++.h>

#define ll long long
#define ld  double
using namespace std;

const int N = 3e5 + 5, mod = 998244353;


int par[N];

int findPar(int u) {
    if(u == par[u]) return u;
    return par[u] = findPar(par[u]);
}

bool sameSet(int u, int v) {
    return findPar(u) == findPar(v);
}

void join(int u, int v) {
    u = findPar(u);
    v = findPar(v);
    par[u] = v;
}

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


    int n, m;
    cin >> n >> m;
    vector<pair<int, pair<int, int> > > edges;
    for(int i = 0; i < m; i++) {
        int city, cost;
        cin >> city >> cost;
        edges.push_back({cost, {0, city}});
    }
    for(int i = 1; i <= n; i++) {
        int cost;
        cin >> cost;
        int nxtNode = i + 1;
        if(i == n) nxtNode = 1;
        edges.push_back({cost, {i, nxtNode}});
    }

    iota(par, par + n + 1, 0);
    sort(edges.begin(), edges.end());

    ll ans = 0;
    for(auto i: edges) {
        int u = i.second.first, v = i.second.second, cost = i.first;
        if(sameSet(u, v)) continue;
        join(u, v);
        ans += cost;
    }
    cout << ans;

    return 0;
}