#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const long long MOD1 = 1000000007;
const long long MOD2 = 998244353;
const long long INF = 1e17;
using P = pair<ll, ll>;
ll mod(ll a, ll m) {
    return (a % m + m) % m;
}
ll extgcd(ll A, ll B, ll& X, ll& Y) {
    ll D = A;
    if (B != 0) {
        D = extgcd(B, A % B, Y, X);
        Y -= (A / B) * X;
    }
    else {
        X = 1; Y = 0;
    }
    return D;
}
pair<ll, ll> ChineseRem(vector<ll>&b, vector<ll>&m) {
    ll r = 0, M = 1;
    for (ll i = 0; i < b.size(); i++) {
        ll p, q;
        ll d = extgcd(M, m[i], p, q);
        if ((b[i] - r) % d != 0) return make_pair(0, -1);
        ll tmp = (b[i] - r) / d * p % (m[i] / d);
        r += M * tmp;
        M *= m[i] / d;
    }
    return make_pair(mod(r, M), M);
}
void solve() {
    vector<ll>X(3), Y(3);
    for (ll i = 0; i < 3; i++) {
        cin >> X[i] >> Y[i];
    }
    pair<ll, ll> ans = ChineseRem(X, Y);
    if (ans == make_pair(0LL, -1LL)) {cout << -1 << endl;return;}
    while (ans.first <= 0) ans.first += ans.second;
    cout << ans.first << endl;
}   
int main() {
    ll T = 1; //cin >> T;
    while (T--) {
        solve();
    }
}