#define _CRT_SECURE_NO_WARNINGS
#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
#include <bits/stdc++.h>
using namespace std;
const int N = 100010;
long long a[N];
pair<int, int> p[N];
int main()
{
    int n, k, m;
    while (~scanf("%d%d%d", &n, &k, &m))
    {
        for (int i = 1; i <= n; i++)
            scanf("%lld", a + i), a[i] += a[i - 1];
        for (int i = 0; i < m; i++)
            scanf("%d%d", &p[i].first, &p[i].second);
        sort(p, p + m);
        priority_queue<int> h;
        long long ans = 0;
        for (int i = 0; i < m; i++)
        {
            h.push(-p[i].second);
            if (h.size() < k) continue;
            if (h.size() > k) h.pop();
            ans = max(ans, a[-h.top()] - a[p[i].first - 1]);
        }
        printf("%lld\n", ans);
    }
    return 0;
}