#include <iostream>
#include <string>
#include <cstdio>
#include <cstring>
#include <vector>
#include <queue>
#include <cmath>
#include <map>
#include <unordered_map>
#include <unordered_set>
using namespace std;

#define ff(i, n) for (int i = 0, END = (n); i < END; i ++)
#define fff(i, n, m) for (int i = (n), END = (m); i <= END; i ++)
#define dff(i, n, m) for (int i = (n), END = (m); i >= END; i --)
#define travel(e, first) for (int e = first, v = vv[first]; ~e; e = nxt[e], v = vv[e])
#define clr(a, b) memset(a, b, sizeof(a))
typedef long long ll;

int gcd(int a, int b) {
    if (b == 0) return a;
    return gcd(b, a % b);
}

int main() {
    int w, x, y, z;
    while (cin >> w >> x >> y >> z) {
        unordered_set<int> s;

        fff (i, w, x) fff (j, y, z) {
            int c = gcd(i, j);
            s.insert((i * 100 + j) / c);
        }

        cout << s.size() << endl;
    }
}