#include <iostream>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <string>
#include <vector>
#include <set>
#include <map>
using namespace std;

const int N = 1005;
int d, n, m;
int a[N], dp[N];
pair<int, int> seg[N];

int main() {
    cin >> d >> n >> m;
    for(int i = 0; i < n; ++i)
        cin >> a[i];
    for(int i = 0; i < m; ++i)
        cin >> seg[i].first >> seg[i].second;
    sort(seg, seg + m);
    sort(a, a+n);
    
    memset(dp, -1, sizeof(dp));
    dp[0] = 0;
    
    for(int i = 0; i < m; ++i) {
        int fs = d+1;
        for(int j = 0; j < n; ++j)
            if(a[j] >= seg[i].first && a[j] <= seg[i].second)
                fs = min(fs, j);
        if(fs == d+1) continue;
        
        int l = (fs == 0 ? 0 : a[fs-1]);
        for(int j = l; j < seg[i].first; ++j)
            if(dp[j] != -1) {
                if(dp[seg[i].second] == -1)
                    dp[seg[i].second] = dp[j] + 1;
                dp[seg[i].second] = min(dp[seg[i].second], dp[j] + 1);
            }
    }
    
    int ans = 100500;
    for(int i = a[n-1]; i <= d; ++i)
        if(dp[i] != -1)
            ans = min(ans, dp[i]);
    cout << ans << endl;
    
    
    return 0;
}