#define PROBLEM "https://yukicoder.me/problems/no/186"

#include <bits/stdc++.h>
using namespace std;

tuple<long long, long long, long long> ext_gcd(long long a, long long b) {
    if(b == 0) return {a, 1, 0};
    auto [d, y, x] = ext_gcd(b, a % b);
    y -= a / b * x;
    return {d, x, y};
}

inline long long safe_mod(long long a, long long m) {
    return (a % m + m) % m;
}

pair<long long, long long> crt(const vector<long long>& b, const vector<long long>& m) {
    assert(b.size() == m.size());
    long long r = 0, M = 1;
    for(int i = 0; i < (int)b.size(); i++) {
        auto [d, p, q] = ext_gcd(M, m[i]);
        if((b[i] - r) % d != 0) return {0, -1};
        long long tmp = (b[i] - r) / d * p % (m[i] / d);
        r += M * tmp;
        M *= m[i] / d;
    }
    r = safe_mod(r, M);
    return {r, M};
}

int main() {
    vector<long long> X(3), Y(3);
    for(int i = 0; i < 3; i++) {
        cin >> X[i] >> Y[i];
    }
    auto [r, m] = crt(X, Y);
    if(r) cout << r << endl;
    else cout << -1 << endl;

    return 0;
}