#include <bits/stdc++.h>

std::pair<long long, long long> crt(std::vector<long long> &a, std::vector<long long> &m){
    assert(a.size() == m.size());
    long long ax = a[0], mx = m[0];

    auto extgcd = [](long long r, long long s) -> std::tuple<long long, long long, long long>{
        bool rev = false;
        if(s < r){
            std::swap(r, s);
            rev = true;
        }
        long long a = 1, b = 0, c = 0, d = 1, k;
        while(s){
            k = r / s;
            a -= k * c;
            b -= k * d;
            std::swap(a, c);
            std::swap(b, d);
            r %= s;
            std::swap(r, s);
        }
        if(rev) return std::make_tuple(b, a, r);
        else return std::make_tuple(a, b, r);
    };

    for(int i = 1, sz = a.size(); i < sz; i++){
        long long my = m[i];
        long long ay = (a[i] % my + my) % my;

        auto [rx, ry, g] = extgcd(mx, my);
        if((ay - ax) % g != 0) return std::make_pair(0, 0);

        long long l = my / g;
        ax = ax + ((ay - ax) / g) % l * rx % l * mx;
        mx *= l;
        if(ax < 0) ax += mx;
    }

    return std::make_pair(ax, mx);
}

int main(){
    std::vector a(3, 0LL), b(3, 0LL);
    for(int i = 0; i < 3; i++) std::cin >> a[i] >> b[i];
    auto res = crt(a, b);
    if(res.second == 0) res.first = -1;
    if(res.first == 0) res.first = res.second;
    std::cout << res.first << "\n";
}