#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
inline void smin(T &a, U b) {
  if (a > b) a = b;
}
template <typename T, typename U>
inline void smax(T &a, U b) {
  if (a < b) a = b;
}
template <class T>
inline void gn(T &first) {
  char c, sg = 0;
  while (c = getchar(), (c > '9' || c < '0') && c != '-')
    ;
  for ((c == '-' ? sg = 1, c = getchar() : 0), first = 0; c >= '0' && c <= '9';
       c = getchar())
    first = (first << 1) + (first << 3) + c - '0';
  if (sg) first = -first;
}
template <class T1, class T2>
inline void gn(T1 &x1, T2 &x2) {
  gn(x1), gn(x2);
}
template <class T1, class T2, class T3>
inline void gn(T1 &x1, T2 &x2, T3 &x3) {
  gn(x1), gn(x2), gn(x3);
}
template <class T1, class T2, class T3, class T4>
inline void gn(T1 &x1, T2 &x2, T3 &x3, T4 &x4) {
  gn(x1), gn(x2), gn(x3), gn(x4);
}
template <class T>
inline void print(T first) {
  if (first < 0) {
    putchar('-');
    return print(-first);
  }
  if (first < 10) {
    putchar('0' + first);
    return;
  }
  print(first / 10);
  putchar(first % 10 + '0');
}
template <class T>
inline void printsp(T first) {
  print(first);
  putchar(' ');
}
template <class T>
inline void println(T first) {
  print(first);
  putchar('\n');
}
template <class T1, class T2>
inline void print(T1 x1, T2 x2) {
  printsp(x1), println(x2);
}
template <class T1, class T2, class T3>
inline void print(T1 x1, T2 x2, T3 x3) {
  printsp(x1), printsp(x2), println(x3);
}
template <class T1, class T2, class T3, class T4>
inline void print(T1 x1, T2 x2, T3 x3, T4 x4) {
  printsp(x1), printsp(x2), printsp(x3), println(x4);
}
int power(int a, int b, int m, int ans = 1) {
  for (; b; b >>= 1, a = 1LL * a * a % m)
    if (b & 1) ans = 1LL * ans * a % m;
  return ans;
}
int first[150010];
double val[150010];
double sum[150010 << 2], mx[150010 << 2], mxl[150010 << 2], mxr[150010 << 2];
void push_up(int u) {
  sum[u] = sum[(u << 1)] + sum[((u << 1) | 1)];
  mx[u] = max(mx[(u << 1)], mx[((u << 1) | 1)]);
  smax(mx[u], mxr[(u << 1)] + mxl[((u << 1) | 1)]);
  mxl[u] = max(mxl[(u << 1)], sum[(u << 1)] + mxl[((u << 1) | 1)]);
  mxr[u] = max(mxr[((u << 1) | 1)], mxr[(u << 1)] + sum[((u << 1) | 1)]);
}
void build(int u, int st, int ed) {
  if (st + 1 == ed) {
    sum[u] = val[st];
    mx[u] = mxl[u] = mxr[u] = max(0., sum[u]);
    return;
  }
  build((u << 1), st, (st + ed >> 1));
  build(((u << 1) | 1), (st + ed >> 1), ed);
  push_up(u);
}
double remain, mmx;
void calc(int u, int st, int ed, int l, int r) {
  smax(l, st);
  smin(r, ed);
  if (l >= r) return;
  if (l == st and r == ed) {
    smax(mmx, mx[u]);
    smax(mmx, remain + mxl[u]);
    remain = max(mxr[u], sum[u] + remain);
    return;
  }
  calc((u << 1), st, (st + ed >> 1), l, r);
  calc(((u << 1) | 1), (st + ed >> 1), ed, l, r);
}
int main() {
  int n, m, c;
  gn(n, m, c);
  for (int i = 0; i < n; i++) {
    gn(first[i]);
  }
  for (int i = 1; i < n; i++) {
    int p;
    gn(p);
    val[i] = (first[i] - first[i - 1]) / 2. - c * p / 100.;
  }
  build(1, 1, n);
  double ans = 0;
  while (m--) {
    int l, r;
    gn(l, r);
    remain = mmx = 0;
    calc(1, 1, n, l, r);
    ans += mmx;
  }
  printf("%.7lf\n", ans);
}
