#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#include <bitset>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }

int exgcd(int a, int b, int &g) {
	int u = 1, v = 0;
	while(b) {
		int t = a / b;
		a -= t * b; swap(a, b);
		u -= t * v; swap(u, v);
	}
	g = a;
	return u;
}

//中国人剰余定理。互いに素であることを仮定しない
//解が存在しない場合には-1を返す
//template<typename Num>
long long crt(long long a1, long long n1, int a2, int n2, long long &resn) {
	int t, g;
	t = exgcd(n1 % n2, n2, g);
	if((a1 - a2) % g != 0) return -1;
	int n2_g = n2 / g;
	int d = (a2 - a1) / g % n2_g;
	int h = (long long)d * t % n2_g;
	if(h < 0) h += n2_g;
	long long n = n1 * n2_g;
	long long a = a1 + n1 * h;
	resn = n;
	return a;
}

int main() {
	ll a = 0, n = 1;
	rep(i, 3) {
		int X, Y;
		cin >> X >> Y;
		a = a == -1 ? -1 : crt(a, n, X, Y, n);
	}
	if(a == 0) a += n;
	printf("%lld\n", a);
	return 0;
}