#include<bits/stdc++.h>
#include<climits>

#define cdbg cerr << "Debug in " << __func__ << ": "
#define q <<  '\n'
#define sp << ' '

#define pb push_back
#define mp make_pair
#define ft first
#define sd second
#define sqr(x) x*x

#define pqe priority_queue
#define ld long double
#define ll long long
#define lll __int128
#define ull unsigned long long
#define pii pair<ll , ll>
#define vi vector<int>

using namespace std;

ll n, m, k, mn = INT_MAX, a , b , c , d, goth, keks,ans;

bool isProstoye(ll x)
{
    bool f = 0;
    for (int i = 2; i*i <= x; i++)
        if (x % i == 0) {f = 1; break;}

    return !f;
}
pii arr[10000];
vi v;
main()
{
    cin >> a >> b >> c >> d;
    goth = keks = (d-c)/2;
    if (c % 2 == 0 || d % 2 == 0) keks++;
    if (d % 2 == 1 || d % 2 == 1) goth++;
    for (int i = a; i <= b; i++)
    {
        if (i >= 2) ans += keks;
        if (i >= 2 && c <= 2) ans--;
        if (i >= 2) ans += goth;
        if (i >= 2 && c <= 5)
        {
            ans--;
            if (c <= 3) ans--;
            if (c == 1) ans--;
        }
        if (i == 1)
        {

            for (int j = c; j <= d; j++)
            {
                if (isProstoye(j)) ans++;
            }

         }



    }
    cout << ans;