#include <iostream>
#include <algorithm>
using namespace std;

int b[1005];
bool a[1005];

int main ()
{
    int n, k, d;
    cin >> n >> k >> d;
    int tt;
    for (int i = 1; i <= k; ++i){
        cin >> tt;
        a[tt] = 1;
    }
    sort (a+1, a+k+1);
    int x, y;
    for (int i = 1; i <= d; ++i){
        cin >> x >> y;
        for (int j = x; j <= y; ++j){
            if (a[j] == 1){
                ++b[i];
            }
        }
    }
    int s = 0, kk = 0;
    int i = 1;
    tt = 1;
    while (s < k){
        ++kk;
        s += b[i];
        ++i;
        if (s > k){
            s = 0;
            kk = 0;
            ++tt;
            i = tt;
        }
    }
    cout << kk;

    return 0;
}