#include <bits/stdc++.h>
// #include <atcoder/all>
// using namespace atcoder;
#define rep(i, n) for (ll i = 0; i < (ll)(n); ++i)
#define rep2(i, s, n) for (ll i = s; i < (ll)(n); i++)
#define repr(i, n) for (ll i = n; i >= 0; i--)
#define pb push_back
#define COUT(x) cout << (x) << "\n"
#define COUTF(x) cout << setprecision(15) << (x) << "\n"
#define ENDL cout << "\n"
#define DF(x) x.erase(x.begin())
#define ALL(x) x.begin(), x.end()
#define SORT(x) sort(ALL(x))
#define RSORT(x) sort(x.rbegin(), x.rend())
#define REVERSE(x) reverse(ALL(x))
#define MAX(x) *max_element(ALL(x))
#define MAXI(x) max_element(ALL(x)) - x.begin()
#define SUM(x) accumulate(ALL(x), 0ll)
#define COUNT(x, y) count(ALL(x), y);
#define ANS cout << ans << "\n"
#define YES cout << "YES\n";
#define NO cout << "NO\n";
#define Yes cout << "Yes\n";
#define No cout << "No\n";
#define init() \
  cin.tie(0);  \
  ios::sync_with_stdio(false)
#define debug(x) cerr << "[debug] " << #x << ": " << x << endl;
#define debugV(v)                       \
  cerr << "[debugV] " << #v << ":";     \
  rep(z, v.size()) cerr << " " << v[z]; \
  cerr << endl;
using namespace std;
using ll = long long;
using ld = long double;
using vll = vector<ll>;
using vvll = vector<vector<ll>>;
using mll = map<ll, ll>;
using qll = queue<ll>;
using P = pair<ll, ll>;
using vp = vector<P>;
using vs = vector<string>;

template <typename T>
inline istream& operator>>(istream& i, vector<T>& v) {
  rep(j, v.size()) i >> v[j];
  return i;
}

template <typename T1, typename T2>
inline istream& operator>>(istream& i, pair<T1, T2>& v) {
  return i >> v.first >> v.second;
}

constexpr ll INF = 0x3f3f3f3f3f3f3f3f;
constexpr ld PI = 3.141592653589793238462643383279;
ll get_digit(ll x) {
  return to_string(x).size();
}

ll gcd(ll x, ll y) {
  return y ? gcd(y, x % y) : x;
}

ll lcm(ll a, ll b) {
  return a / gcd(a, b) * b;
}

template <class T>
void chmax(T& a, const T& b) {
  if (a < b) a = b;
}

template <class T>
void chmin(T& a, const T& b) {
  if (b < a) a = b;
}

ll mod_pow(ll x, ll n, ll mod) {
  if (n == 0) return 1;
  ll res = mod_pow(x * x % mod, n / 2, mod);
  if (n & 1) res *= x;
  res %= mod;
  return res;
}

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

ll ext_gcd(ll a, ll b, ll& p, ll& q) {
  if (b == 0) {
    p = 1;
    q = 0;
    return a;
  }
  ll d = ext_gcd(b, a % b, q, p);
  q -= a / b * p;
  return d;
}

P crt(ll b1, ll m1, ll b2, ll m2) {
  ll p, q;
  ll d = ext_gcd(m1, m2, p, q);
  if ((b2 - b1) % d != 0) return {0, -1};
  ll m = lcm(m1, m2);
  ll tmp = (b2 - b1) / d * p % (m2 / d);
  ll r = mod(b1 + m1 * tmp, m);
  return make_pair(r, m);
}

signed main() {
  init();
  ll x1, y1, x2, y2, x3, y3;
  cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
  P p = crt(x1, y1, x2, y2);
  P ans = crt(p.first, p.second, x3, y3);
  if (p.second == -1 or ans.second == -1) {
    COUT(-1);
    return 0;
  }
  COUT(ans.first);
  return 0;
}