#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

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

pair<long long, long long> crt(const vector<long long>& rs, const vector<long long>& ms){
    if(rs.empty() || ms.empty())    return make_pair(0, 1);
    long long R = rs[0], M = ms[0];
    for(int i = 1; i < (int)rs.size(); ++i){
        long long p, q, r = rs[i], m = ms[i];
        if(M < m){
            swap(M, m);
            swap(R, r);
        }
        long long d = extgcd(M, m, p, q);
        if((r - R) % d != 0)    return make_pair(0, -1);
        long long modulo = m / d;
        long long tmp = (r - R) / d % modulo * p % modulo;
        R += M * tmp;
        M *= modulo;
    }
    if((R %= M) < 0)    R += M;
    return make_pair(R, M);
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    vector<ll> X(3), Y(3);
    for(int i = 0; i < 3; ++i)  cin >> X[i] >> Y[i];
    auto ans = crt(X, Y);
    cout << (ans.second == -1 ? ans.second : ans.first) << endl;

    return 0;
}