#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vl vector<ll>
#define ov4(a, b, c, d, name, ...) name
#define rep3(i, a, b, c) for(ll i = (a); i < (b); i += (c))
#define rep2(i, a, b) rep3(i, a, b, 1)
#define rep1(i, n) rep2(i, 0, n)
#define rep0(n) rep1(aaaaa, n)
#define rep(...) ov4(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
#define per(i, a, b) for(ll i = (a)-1; i >= (b); i--)
#define fore(e, v) for(auto&& e : v)
#define all(a) begin(a), end(a)
#define sz(a) (int)(a.size())
#define lb(v, x) (lower_bound(all(v), x) - begin(v))
#define eb emplace_back

template<typename T, typename S> bool chmin(T& a, const S& b) { return a > b ? a = b, 1 : 0; }
template<typename T, typename S> bool chmax(T& a, const S& b) { return a < b ? a = b, 1 : 0; }
 
const int INF = 1e9 + 100;
const ll INFL = 3e18 + 100;
 
#define i128 __int128_t
 
struct _ {
   _() { cin.tie(0)->sync_with_stdio(0), cout.tie(0); }
} __;

void debug(auto ...vs) {
    ((cerr << vs << " "), ...) << endl;
}
ll extgcd(ll a, ll b, ll& x, ll& y) {
   // assert(a >= 0 && b >= 0);
   if(!b) return x = 1, y = 0, a;
   ll d = extgcd(b, a % b, y, x);
   y -= a / b * x;
   return d;
}
ll inv_mod(ll x, ll md) {
   ll y, z;
   extgcd(x, md, y, z);
   return (y % md + md) % md;
}

void solve() {
	int n;
	cin >> n;
	ll k, m;cin >> k >> m;
	vl b(n + 1), c(n + 1);
	rep(i, n) cin >> b[i];
	rep(i, n) {
		cin >> c[i];
		c[i] %= m;
	}
	b.back() = 1;
	c.back() = 0;
	// debug("!");
	
	ll s = 0;
	int j;
	ll rj;
	ll t = 0;
	rep(i, n + 1) {
		if (s + b[i] <= k) {
			s += b[i];
			t += b[i] * c[i] % m;
			t %= m;
		}
		else {
			t += (k - s) * c[i] % m;
			t %= m;
			rj = s + b[i] - k;
			j = i;
			break;
		}
	}

	auto calc = [&](ll r, ll t, ll z) -> ll {
		if (z == 0) {
			if (t == 0) return r;
			else return 0;
		}
		ll g = gcd(m, z);
		if (t % g) return 0;
		t /= g;
		z /= g;
		int M = m / g;
		ll i0 = inv_mod(z, M) * (M - t) % M;

		ll ans = r / M;
		if (i0 < r % M)ans++;
		return ans;
	};

	int i = 0;
	ll ri = b[i];
	ll ans = 0;
	while (j < n + 1) {
		int r = min(ri, rj);
		ans += calc(r, t, (c[j]-c[i] + m) % m);
		// debug(r, t,  (c[j]-c[i] + m) % m,calc(r, t, (c[j]-c[i] + m) % m));
		t += (c[j] - c[i] + m) % m * r % m;
		t %= m;
		if (ri < rj) {
			rj -= ri;
			i += 1;
			ri = b[i];
		}
		else {
			ri -= rj;
			j += 1;
			if (j < n + 1) rj = b[j];
		}
	}
	cout << ans << endl;
}

int main(){
    int T = 1;
    // int T;cin >> T;
    while(T--) {

        solve();
    }
    
}