#include <iostream>
#include <vector>

using namespace std;

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

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

int main() {
	vector<long long> b(3), m(3);
	for (int i = 0; i < 3; i++) cin >> b[i] >> m[i];

	pair<long long, long long> crt = CRT(b, m);
	if (crt.first) cout << crt.first << endl;
	else cout << -1 << endl;
	return 0;
}