#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (int)(n); i++)
#define REP(i,n) for (int i = 1; i < (int)(n); i++)
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define debug(var) do{cout << #var << " : "; view(var);}while(0)
template<class T> bool chmin(T &a, T b) {if(a>b) {a=b;return 1;}return 0;}
template<class T> bool chmax(T &a, T b) {if(a<b) {a=b;return 1;}return 0;}
using namespace std;
template<class T> void view(T e) {cout << e << endl;}
template<class T> void view(const vector<T> &v) {for(const auto &e : v){cout << e << " ";} cout << endl;}
template<class T> void view(const vector<vector<T>> &vv) {for(const auto &v : vv){view(v);}}
using vint = vector<int>;
using vvint = vector<vector<int>>;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vector<ll>>;
using P = pair<int,int>;
const int inf = 1<<30;
const ll inf_l = 1LL<<61;
const int MAX = 1e5;

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

ll ext_gcd(ll a, ll b, ll &x, ll &y) {
    if (b == 0) {
        x = 1; y = 0;
        return a;
    }
    ll d = ext_gcd(b, a % b, y, x); //xにyの値を入れている
    y -= a / b * x;
    return d;
}

pair<ll, ll> chinese_rem(const vector<ll> &r, const vector<ll> &m) {
    ll r0 = 0, m0 = 1;
    for (int i = 0; i < (int)r.size(); i++) {
        ll r1 = mod(r[i], m[i]), m1 = m[i];
        if (m0 < m1) {
            swap(m0, m1);
            swap(r0, r1);
        }
        if (m0 % m1 == 0) {
            //r0 ≡ r1 (mod m1)
            if (r0 % m1 != r1) return {0, 0};
            continue;
        }
        ll p, q;
        ll g = ext_gcd(m0, m1, p, q);
        ll u1 = m1 / g;
        if ((r1 - r0) % g != 0) return {0, 0};
        ll tmp = (r1 - r0) / g % u1 * p % u1;
        r0 += m0 * tmp;
        m0 *= u1;
        if (r0 < 0) r0 += m0;
    }
    return {r0, m0};
}

int main() {
    vll x(3), y(3);
    rep(i,3) cin >> x[i] >> y[i];
    pair<ll, ll> ans = chinese_rem(x, y);
    if (ans.second == 0) cout << -1 << endl;
    else if (ans.first == 0) cout << ans.second << endl;
    else cout << ans.first << endl;
}