#include <bits/stdc++.h>

using namespace std;
using ll = long long;

constexpr int inf = 1e9 + 7;

void ckmax(int &x, int y) {
    if (x < y) {
        x = y;
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n[2], k;
    cin >> n[0] >> n[1] >> k;

    vector<pair<int, int>> seg[2];
    vector<int> yy[2], dp[2], all;
    
    for (int t = 0; t < 2; ++t) {
        for (int i = 0; i < n[t]; ++i) {
            int l, r;
            cin >> l >> r;
            if (t == 0 && l == 0) {
                was0 = true;
            }
            seg[t].emplace_back(l, r - 1);
            yy[t].push_back(l), yy[t].push_back(r - 1);
        }
        yy[t].push_back(0);
        sort(seg[t].begin(), seg[t].end());
        sort(yy[t].begin(), yy[t].end());
        yy[t].resize(unique(yy[t].begin(), yy[t].end()) - yy[t].begin());
        dp[t].assign(yy[t].size(), -inf);
    }

    all.resize(yy[0].size() + yy[1].size());
    merge(yy[0].begin(), yy[0].end(), yy[1].begin(), yy[1].end(), all.begin());
    all.resize(unique(all.begin(), all.end()) - all.begin());

    auto in = [&](int t, int i) -> int {
        auto it = lower_bound(seg[t].begin(), seg[t].end(), pair<int, int>{i, inf});
        if (it == seg[t].begin() || prev(it)->second < i) {
            return false;
        } else {
            return it - seg[t].begin();
        }
    };

    auto isl = [&](int s, int x) {
        int i = in(s, x);
        return i && seg[s][i - 1].first == x;
    };

    auto find = [&](int s, int x) -> int {
        return lower_bound(yy[s].begin(), yy[s].end(), x) - yy[s].begin();
    };

    dp[0][0] = isl(0, 0);

    int siz[2]{int(size(seg[0])), int(size(seg[1]))};

    for (int x : all) {
        for (int s = 0; s < 2; ++s) {
            int i = find(s, x);
            if (i >= size(yy[s]) || yy[s][i] != x) {
                continue;
            }
            int nxt = find(s, x + 1);
            if (nxt < siz[s]) {
                ckmax(dp[s][nxt], dp[s][i] + isl(s, yy[s][nxt]));
            }
            nxt = find(s ^ 1, x + k);
            if (nxt < siz[s ^ 1]) {
                ckmax(dp[s ^ 1][nxt], dp[s][i] + isl(s ^ 1, yy[s ^ 1][nxt]));
            }
            int cnt = 0;
            for (int t = 1; ; ++t) {
                int ns = s ^ (t & 1);
                int nx = x + k * t;
                if (!in(ns, nx)) {
                    break;
                } else {
                    cnt += 1;
                }
            }
            if (cnt > 0) {
                int del = cnt % 2 == 0;
                if (del) {
                    cnt -= 1;
                }
                int nx = x + k * cnt;
                int p = in(s ^ 1, nx);
                assert(p > 0);
                p -= 1;
                ckmax(dp[s ^ 1][find(s ^ 1, seg[s ^ 1][p].second)], dp[s][i] + cnt);
                if (del) {
                    cnt += 1;
                }
            }
            if (cnt > 1) {
                int del = cnt % 2 == 1;
                if (del) {
                    cnt -= 1;
                }
                int nx = x + k * cnt;
                int p = in(s, nx);
                assert(p > 0);
                p -= 1;
                ckmax(dp[s][find(s, seg[s][p].second)], dp[s][i] + cnt);
                if (del) {
                    cnt += 1;
                }
            }
            for (int c : {cnt, cnt + 1}) {
                int ns = s ^ (c & 1);
                int ni = find(ns, x + c * k);
                if (ni < siz[ns]) {
                    ckmax(dp[ns][ni], dp[s][i] + c);
                }
            }
        }
    }

    int ans = max(*max_element(dp[0].begin(), dp[0].end()), *max_element(dp[1].begin(), dp[1].end()));

    cout << ans << '\n';

    return 0;
}

answer.code: In function ‘int main()’:
answer.code:29:17: error: ‘was0’ was not declared in this scope
   29 |                 was0 = true;
      |                 ^~~~