#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vll = vector<ll>;

#define rep(i, x) for (ll i = 0; i < x; ++i)

template <typename T>
T extgcd(T a, T b, T &x, T &y) {
  T d = a;
  if (b != 0) {
    d = extgcd(b, a % b, y, x);
    y -= (a / b) * x;
  } else {
    x = 1;
    y = 0;
  }
  return d;
}

ll safe_mod(ll a, ll m)
{
    return (a % m + m) % m;
}

int main ()
{
    ll n = 3;
    vll R(n), M(n);
    rep(i, n)
    {
        cin >> R[i] >> M[i];
    }

    ll r = 0;
    ll m = 1;

    rep(i, n)
    {
        ll p, q;
        ll d = extgcd(m, M[i], p, q);

        if ((R[i] - r) % d != 0)
        {
            cout << -1 << endl;
            return 0;
        }

        ll m2_d = M[i] / d;
        ll m_next = m * M[i] / d; // mとM[i]の最小公倍数 m_nextを法とする剰余環が中国式剰余定理より同型。

        ll tmp = safe_mod(p, m2_d) * safe_mod((R[i] - r) / d, m2_d) % m2_d;
        ll r_next = safe_mod(r + tmp * m, m_next);

        r = r_next;
        m = m_next;
    }
    


    // 答えは正の整数でなくてはならない
    if (r == 0)
    {
        r += m;
    }
    cout << r << endl;
}