#include <bits/stdc++.h>
using namespace std;
inline int read(void) {
  int x = 0;
  char c = getchar();
  while (c > '9' || c < '0') c = getchar();
  while (c >= '0' && c <= '9') x = x * 10 + (c - '0'), c = getchar();
  return x;
}
const int N = 150010, M = 300010;
int n, m, c;
int loc[N], p[N];
struct xint {
  double max_left, max_right, sum, res;
  xint() {}
  xint(double A) : max_left(A), max_right(A), sum(A), res(A) {}
  inline void print(void) {
    printf("%.2lf %.2lf %.2lf %.2lf\n", sum, max_left, max_right, res);
    puts("");
  }
} tr[N * 5];
xint update(xint lc, xint rc) {
  xint k;
  k.sum = lc.sum + rc.sum;
  k.max_left = max(lc.max_left, lc.sum + rc.max_left);
  k.max_right = max(rc.max_right, lc.max_right + rc.sum);
  k.res = max(lc.res, rc.res);
  k.res = max(k.res, lc.max_right + rc.max_left);
  return k;
}
void build(int k, int l, int r) {
  if (l == r) {
    double P = (double)p[l] / 100.0;
    double tmp = (double)(loc[l + 1] - loc[l]) / 2 - P * c;
    tr[k] = xint(tmp);
    return;
  }
  int mid = (l + r) >> 1;
  int lc = k << 1, rc = k << 1 | 1;
  build(lc, l, mid);
  build(rc, mid + 1, r);
  tr[k] = update(tr[lc], tr[rc]);
}
xint query(int k, int l, int r, int x, int y) {
  if (x <= l && r <= y) return tr[k];
  if (l > r) return 0;
  int mid = (l + r) >> 1;
  int lc = k << 1, rc = k << 1 | 1;
  if (y <= mid) return query(lc, l, mid, x, y);
  if (x > mid) return query(rc, mid + 1, r, x, y);
  xint tmp1 = query(lc, l, mid, x, y);
  xint tmp2 = query(rc, mid + 1, r, x, y);
  return update(tmp1, tmp2);
}
int main(void) {
  n = read(), m = read(), c = read();
  for (int i = 1; i <= n; ++i) loc[i] = read();
  for (int i = 1; i < n; ++i) p[i] = read();
  build(1, 1, n - 1);
  double ans = 0;
  for (int i = 1; i <= m; ++i) {
    int l = read(), r = read();
    xint tmp = query(1, 1, n - 1, l, r - 1);
    ans += max(tmp.res, 0.0);
  }
  printf("%.8lf\n", ans);
  return 0;
}
