#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<ll, int> pii;
const ll mod = 998244353;
const ll inf = 1e18;
const int maxn = 5e4 + 5;

int m, q, val[maxn], id1[maxn];
int w[maxn], id2[maxn], p[maxn][150], sz[maxn], sz2[maxn];
ll n, d[maxn], qu[maxn], qv[maxn], cnt[maxn], reald[maxn][150], times[maxn][150];
bool vs[maxn];

void calcdi()
{
    priority_queue<pii, vector<pii>, greater<pii> > pq;
    for (int i = 1; i <= m; i++)
    {
        while (pq.size()) pq.pop(); pq.push(make_pair(inf, -1));
        for (int j = 1; j <= sz[i - 1]; j++) pq.push(make_pair(d[p[i - 1][j]], p[i - 1][j]));
        pq.push(make_pair(d[id1[i]], id1[i]));

        ll nw = n, delt = 0;
        while (1)
        {
            while (pq.top().first == delt) pq.pop();
            ll x = pq.top().first - delt;
            if (x == inf - delt) break; reald[i][++sz2[i]] = x;
            if (!vs[pq.top().second]) p[i][++sz[i]] = pq.top().second, vs[pq.top().second] = 1;
            while (pq.top().first != inf && (pq.top().first - delt) % x == 0) pq.pop();
            if (pq.top().first == inf)
            {
                times[i][sz2[i]] = nw / x;
                cnt[i] += min(nw, x);
                break;
            }
            ll y = pq.top().first - delt, z = y / x;
            if (nw <= z * x)
            {
                times[i][sz2[i]] = nw / x;
                cnt[i] += min(nw, x); break;
            }
            times[i][sz2[i]] = z, nw -= x * z, cnt[i] += (nw > x ? 0 : x - nw), delt += z * x;
            x += delt; pq.push(make_pair(x, p[i][sz[i]]));
        }
        for (int j = 1; j <= sz[i]; j++) vs[p[i][j]] = 0;
    }
}

ll findid(ll x, int tid)
{
    if (!tid) return x; ll nw = n;
    for (int i = 1; i <= sz2[tid]; i++)
    {
        ll nd = reald[tid][i], nt = times[tid][i];
        if (x < nw - nd)
        {
            ll c = min(nt, (nw - x - 1) / nd);
            nt -= c, nw -= c * nd;
            if (!nt) continue;
        }
        if (x >= nd)
        {
            ll c = min(nt, x / nd);
            nt -= c, nw -= c * nd, x -= c * nd;
            if (!nt) continue;
        }
        return x;
    }
    return x;
}

vector<pii> Mg[maxn], tb;
void solve(int l, int r, const vector<int>& nw)
{
    int len = nw.size();
    if (len <= 1) return;
    if (l == r)
    {
        for (int i = 1; i < len; i++) Mg[l].emplace_back(make_pair(nw[i - 1], nw[i]));
        return;
    }
    int mid = (l + r - 1) >> 1;
    vector<pii> tb; tb.resize(len);
    for (int i = 0; i < len; i++)
    {
        ll x = nw[i];
        tb[i] = make_pair(findid(x <= q ? qu[x] : qv[x - q], mid), x);
    }
    sort(tb.begin(), tb.end());
    
    vector<int> S = {tb[0].second};
    for (int i = 1; i < len; i++)
        if (tb[i].first != tb[i - 1].first) S.emplace_back(tb[i].second);
    solve(mid + 1, r, S);

    S = {tb[0].second};
    for (int i = 1; i < tb.size(); i++)
    {
        if (tb[i].first == tb[i - 1].first) S.emplace_back(tb[i].second);
        else solve(l, mid, S), S = {tb[i].second};
    }
    solve(l, mid, S);
}

struct DSU
{
    int fa[maxn << 1];
    inline int findfa(int x) { return x == fa[x] ? x : fa[x] = findfa(fa[x]); }
    void init(int k) { for (int i = 1; i <= k; i++) fa[i] = i;}
    bool merge(int x, int y)
    {
        x = findfa(x), y = findfa(y);
        if (x == y) return 0;
        fa[x] = y; return 1;
    }
}dsu;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    cin >> n >> m >> q; vector<int> nw; nw.resize(q << 1), dsu.init(q << 1);
    for (int i = 1; i <= m; i++) cin >> d[i] >> val[i], id1[i] = i;
    for (int i = 1; i <= q; i++) cin >> qu[i] >> qv[i] >> w[i], id2[i] = i;
    for (int i = 0; i < (q << 1); i++) nw[i] = i + 1;
    sort(id1 + 1, id1 + m + 1, [&](int a, int b) { return val[a] < val[b]; });
    sort(id2 + 1, id2 + q + 1, [&](int a, int b) { return w[a] < w[b]; });

    calcdi(); cnt[0] = n;
    if (nw.size()) solve(0, m + 1, nw);

    int cur = 0, i = 1, j = 1, pid = 0; ll lst = n, ans = 0;
    for (auto [a, b] : Mg[0]) dsu.merge(a, b);
    while (i <= m || j <= q)
    {
        if (i <= m && (j > q || val[id1[i]] <= w[id2[j]]))
        {
            for (auto [a, b] : Mg[i]) if (!dsu.merge(a, b)) cur--;
            (ans += (lst - (cnt[i] - cur)) % mod * val[id1[i]]) %= mod; lst = cnt[i] - cur; i++;
        }
        else
        {
            if (dsu.merge(id2[j], id2[j] + q)) cur++;
            (ans += (lst - (cnt[i - 1] - cur)) % mod * w[id2[j]]) %= mod; lst = cnt[i - 1] - cur; j++;
        }
    }
    cout << ans;
    return 0;
}