#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define rrep(i, b, a) for (int i = b; i-- > (a);)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using vi = vector<int>;
template <class T>
bool chmin(T& lhs, T rhs) {
    return lhs > rhs ? (lhs = rhs, true) : false;
}
template <class T>
bool chmax(T& lhs, T rhs) {
    return lhs < rhs ? (lhs = rhs, true) : false;
}
struct IOIO {
    IOIO() {
        cin.tie(0)->sync_with_stdio(0);
    }
} ioio;

pair<ll, ll> extgcd(ll a, ll b) {
    if (b == 0) return {1, 0};
    auto [x, y] = extgcd(b, a % b);
    return {y, x - (a / b) * y};
}

ll inv(ll x, ll m) {
    auto [res, _] = extgcd(x, m);
    return (res % m + m) % m;
}

ll garner(vector<ll> r, vector<ll> m) {
    int n = ssize(r);
    ll x = r[0] % m[0];
    ll p = m[0];
    rep(i, 1, n) {
        if (m[i] > p) swap(m[i], p), swap(r[i], x);
        if (p % m[i] == 0) {
            if (x % m[i] != r[i]) return -1;
        } else {
            ll g = gcd(p, m[i]);
            if ((r[i] - x) % g != 0) return -1;
            ll t = ((r[i] - x) / g) % (m[i] / g) * inv(p / g, m[i] / g) % (m[i] / g);
            x += p * t;
            p *= m[i] / g;
            x = (x % p + p) % p;
        }
    }
    return (x == 0 ? x + p : x);
}

int main() {
    int n = 3;
    vector<ll> r(n), m(n);
    rep(i, 0, n) cin >> r[i] >> m[i];
    cout << garner(r, m) << '\n';
}