#define _CRT_SECURE_NO_WARNINGS
//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
//#define int ll
//#define endl "\n"
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
#define all(c) (c).begin(), (c).end()
#define loop(i,a,b) for(ll i=a; i<ll(b); i++)
#define rep(i,b) loop(i,0,b)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
template<class T> ostream & operator<<(ostream & os, vector<T> const &);
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream &, tuple<T...> const &){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream & os, tuple<T...> const & t){ os << (n==0?"":" ") << get<n>(t); _ot<n+1>(os, t); }
template<class...T> ostream & operator<<(ostream & os, tuple<T...> const & t){ _ot<0>(os, t); return os; }
template<class T, class U> ostream & operator<<(ostream & os, pair<T,U> const & p){ return os << "(" << p.first << ", " << p.second << ") "; }
template<class T> ostream & operator<<(ostream & os, vector<T> const & v){ rep(i,v.size()) os << v[i] << (i+1==(int)v.size()?"":" "); return os; }
template<class T> inline bool chmax(T & x, T const & y){ return x<y ? x=y,true : false; }
template<class T> inline bool chmin(T & x, T const & y){ return x>y ? x=y,true : false; }
#ifdef DEBUG
#define dump(...) (cerr<<#__VA_ARGS__<<" = "<<mt(__VA_ARGS__)<<" ["<<__LINE__<<"]"<<endl)
#else
#define dump(...)
#endif
// ll const mod = 1000000007;
// ll const inf = 1LL<<60;

/* m[i] の積のオーバーフローに注意 */

template<class T>
T gcd(T a, T b) {
    return __gcd(a,b); // GCC拡張
    // return b != 0 ? gcd(b, a % b) : a;
}

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

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


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

ll mod_inv(ll a, ll m) {
    ll x, y;
    extgcd(a, m, x, y);
    return (m + x % m) % m;
}

pair<ll, ll> linear_congruence(const vector<ll>& A, const vector<ll>& B,
                                 const vector<ll>& M) {
    ll x = 0, m = 1;
    rep(i,A.size()){
        ll a = A[i] * m, b = B[i] - A[i] * x, d = gcd(M[i], a);
        if (b % d != 0) return mp(0,-1);
        ll t = b / d * mod_inv(a / d, M[i] / d) % (M[i] / d);
        x = x + m * t;
        m *= M[i] / d;
    }
    return make_pair(x % m, m);
}

int main(){
    int N = 3;
    vector<ll> X(N), Y(N);
    rep(i,N) cin >> X[i] >> Y[i];
    vector<ll> A(N);
    rep(i,N) A[i] = 1;
    auto ans = linear_congruence(A,X,Y);
    if(ans.second == -1){
        cout << -1 << endl;
    } else {
        cout << ans.first << endl;
    }
}