#include <bits/stdc++.h>
using namespace std;
struct tree {
  int l, r, c, p;
};
int n, K, m, r;
long long res, a[10000011], b[10000011];
bool cmp1(tree a, tree b) { return a.l < b.l; }
bool cmp2(tree a, tree b) { return a.r < b.r; }
void update(int x, int l, int r, int c, int p) {
  if (l == r) {
    a[x] += c, b[x] += 1ll * l * c;
    return;
  }
  int mid = (l + r) >> 1;
  if (p <= mid)
    update(x << 1, l, mid, c, p);
  else
    update(x << 1 | 1, mid + 1, r, c, p);
  a[x] = a[x << 1] + a[x << 1 | 1], b[x] = b[x << 1] + b[x << 1 | 1];
  return;
}
long long query(int x, int l, int r, int p) {
  if (l == r) {
    if (p <= a[x]) return 1ll * l * p;
    return b[x];
  }
  int mid = (l + r) >> 1;
  if (a[x << 1] >= p) return query(x << 1, l, mid, p);
  return query(x << 1 | 1, mid + 1, r, p - a[x << 1]) + b[x << 1];
}
int main() {
  scanf("%d%d%d", &n, &K, &m);
  tree a[m + 1], b[m + 1];
  for (int i = 1; i <= m; i++)
    scanf("%d%d%d%d", &a[i].l, &a[i].r, &a[i].c, &a[i].p), b[i] = a[i];
  for (int i = 1; i <= m; i++) r = max(r, a[i].p);
  sort(a + 1, a + m + 1, cmp1);
  sort(b + 1, b + m + 1, cmp2);
  for (int i = 1, j = 1, k = 1; i <= n; i++) {
    while (j <= m && a[j].l == i) update(1, 1, r, a[j].c, a[j].p), j++;
    res += query(1, 1, r, K);
    while (k <= m && b[k].r == i) update(1, 1, r, -b[k].c, b[k].p), k++;
  }
  printf("%lld", res);
  return 0;
}
