#include <bits/stdc++.h>

#define el '\n'
#define ll long long
#define ld long double

#define Beevo ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

using namespace std;

const int N = 1e5 + 5;


struct DSU {
    vector<int> sz, par;

    DSU() {
        sz.resize(N);
        par.resize(N);

        for (int i = 0; i < N; i++)
            par[i] = i, sz[i] = 1;
    }

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

        return par[u] = findSet(par[u]);
    }

    void unionSet(int u, int v) {
        u = findSet(u);
        v = findSet(v);

        if (u != v) {
            if (sz[u] < sz[v])
                swap(u, v);

            par[v] = u;
            sz[u] += sz[v];
        }
    }
} dsu;

void testCase() {
    int n, m;
    cin >> n >> m;

    ll c;
    int u;
    vector<pair<int, pair<int, int>>> v;
    for (int i = 0; i < m; i++) {
        cin >> u >> c;

        u--;

        v.push_back({c, {u, n}});
    }

    for (int i = 0; i < n; i++) {
        cin >> c;

        v.push_back({c, {i, (i + 1) % n}});
    }

    sort(v.begin(), v.end());

    ll sum = 0;
    for (auto &i: v) {
        if (dsu.findSet(i.second.first) != dsu.findSet(i.second.second)) {
            sum += i.first;

            dsu.unionSet(i.second.first, i.second.second);
        }
    }

    cout << sum;
}

signed main() {
    Beevo

    int T = 1;
//    cin >> T;

    while (T--)
        testCase();

    return 0;
}