//看看会不会爆int!数组会不会少了一维！

//取物问题一定要小心先手胜利的条件

#include <bits/stdc++.h>

using namespace std;

#pragma comment(linker,"/STACK:102400000,102400000")

#define LL long long

#define ALL(a) a.begin(), a.end()

#define pb push_back

#define mk make_pair

#define fi first

#define se second

#define haha printf("haha\n")

const int maxn =  + ;

int n, k, m;

LL a[maxn], sum[maxn];

vector<int> ve[maxn];

struct Point{

    int rb;

    bool operator < (const Point& a) const{

        return a.rb < rb;

    }

    Point(int x = ): rb(x){};

};

int main(){

    while (scanf("%d%d%d", &n, &k, &m) == ){

        memset(sum, , sizeof(sum));

        for (int i = ; i <= n; i++){

            scanf("%lld", a + i);

            sum[i] = sum[i - ] + a[i];

            ve[i].clear();

        }

        for (int i = ; i <= m; i++){

            int u, v; scanf("%d%d", &u, &v);

            ve[u].push_back(v);

        }

        LL ans = ;

        priority_queue<Point> que;

        for (int i = ; i <= n; i++){

            for (int j = ; j < ve[i].size(); j++){

                que.push(Point(ve[i][j]));

            }

            while (que.size() > k) que.pop();

            if (que.size() == k) ans = max(ans, sum[que.top().rb] - sum[i - ]);

        }

        printf("%lld\n", ans);

    }

    return ;

}