#include <iostream>
#include <algorithm>
#include <vector>

#define X first
#define Y second

using namespace std;

int D, N, M;

bool skip[1000 + 10];

vector<int> jmp[1000 + 10];


int DP[1000 + 10];

int main() {
    cin >> D >> N >> M;

    for(int i = 1; i <= N; ++i) {
        int t;
        cin >> t;
        skip[t] = 1;
    }

    int x, y;

    for(int i = 1; i <= M; ++i) {
        cin >> x >> y;
        jmp[x].push_back(y);
    }

    for(int i = 1; i <= D; ++i)
        DP[i] = (1 << 30);

    for(int i = 1; i <= D; ++i) {
        for(auto j: jmp[i]) {
            DP[j] = min(DP[j], 1 + DP[i - 1]);
        }
        if(skip[i] == 0)
            DP[i] = min(DP[i], DP[i - 1]);
    }

    int mn = 1 << 30;

    for(int i = D; i >= 1; --i) {
        if(DP[i] < mn)
            mn = DP[i];
        if(skip[i])
            break;
    }

    cout << mn << "\n";

    return 0;
}