#include <bits/stdc++.h>
using namespace std;
using LL = long long int;
#define incID(i, l, r) for(int i = (l)    ; i <  (r); ++i)
#define decID(i, l, r) for(int i = (r) - 1; i >= (l); --i)
#define incII(i, l, r) for(int i = (l)    ; i <= (r); ++i)
#define decII(i, l, r) for(int i = (r)    ; i >= (l); --i)
#define inc(i, n)  incID(i, 0, n)
#define dec(i, n)  decID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec1(i, n) decII(i, 1, n)
#define inID(v, l, r) ((l) <= (v) && (v) <  (r))
#define inII(v, l, r) ((l) <= (v) && (v) <= (r))
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define FI first
#define SE second
#define FR front()
#define BA back()
#define ALL(v) v.begin(), v.end()
#define RALL(v) v.rbegin(), v.rend()
auto setmin   = [](auto & a, auto b) { return (b <  a ? a = b, true : false); };
auto setmax   = [](auto & a, auto b) { return (b >  a ? a = b, true : false); };
auto setmineq = [](auto & a, auto b) { return (b <= a ? a = b, true : false); };
auto setmaxeq = [](auto & a, auto b) { return (b >= a ? a = b, true : false); };
#define SI(v) static_cast<int>(v.size())
#define RF(e, v) for(auto & e: v)
#define until(e) while(! (e))
#define if_not(e) if(! (e))
#define ef else if
#define UR assert(false)
#define IN(T, ...) T __VA_ARGS__; IN_(__VA_ARGS__);
void IN_() { };
template<typename T, typename ... U> void IN_(T & a, U & ... b) { cin >> a; IN_(b ...); };
template<typename T> void OUT(T && a) { cout << a << endl; }
template<typename T, typename ... U> void OUT(T && a, U && ... b) { cout << a << " "; OUT(b ...); }

// ---- ----

template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
auto fl = [](auto a, auto b) { assert(b != 0); return a / b - (a % b != 0 && ((a >= 0) != (b >= 0)) ? 1 : 0); };
auto ce = [](auto a, auto b) { assert(b != 0); return a / b + (a % b != 0 && ((a >= 0) == (b >= 0)) ? 1 : 0); };
auto mo = [](auto a, auto b) { assert(b != 0); a %= b; if(a < 0) { a += abs(b); } return a; };

template<typename T> class CRT {
private:
	T A, M;
	bool ok, positive;
	array<T, 3> ext_gcd(T a, T b) {
		if(b == 0) { return { 1, 0, a }; }
		auto x = ext_gcd(b, a % b);
		return { x[1], x[0] - (a / b) * x[1], x[2] };
	}
	T multi(T a, T b, T m) { // a * b % m
		a %= m;
		b %= m;
		T B = 1'000'000'000;
		T au = a / B, ad = a % B;
		T bu = b / B, bd = b % B;
		T s0 = ad * bd % m;
		T s1 = (au * bd + ad * bu) % m;
		T s2 = au * bu % m;
		inc(i,  9) { (s1 *= 10) %= m; }
		inc(i, 18) { (s2 *= 10) %= m; }
		return (s0 + s1 + s2) % m;
	}
public:
	CRT(bool p = false) {
		A = 0;
		M = 1;
		ok = true;
		positive = p;
	}
	void add(T a, T m) {
		assert(inID(a, 0, m));
		if(! ok) { return; }
		auto qq = ext_gcd(M, -m);
		assert(M * qq[0] - m * qq[1] == qq[2]);
		if((a - A) % qq[2] != 0) { ok = false; return; }
		T d = (a - A) / qq[2];
		T L = lcm(M, m);
		T Q = multi(qq[0], d, m);
		T q = multi(qq[1], d, M);
		T X = M * Q + A;
		T x = m * q + a;
		assert(X == x);
		if(x < 0) {
			Q += ce(-X, L) * L / M;
			q += ce(-x, L) * L / m;
			X = M * Q + A;
			x = m * q + a;
		}
		assert(Q >= 0 && q >= 0);
		assert(M * Q + A == m * q + a);
		A = M * Q + A;
		M = L;
		assert(inID(A, 0, M));
	}
	optional<T> get_a() {
		optional<T> a;
		if(ok) { a = (positive && A == 0 ? M : A); }
		return a;
	}
	T get_m() { return M; }
};

int main() {
	CRT<LL> crt(true);
	inc(i, 3) {
		IN(LL, a, m);
		crt.add(a, m);
	}
	OUT(crt.get_a().value_or(-1));
}