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

#define ll long long
#define ull unsigned long long
#define ld  long double

using LL = long long; using ULL = unsigned long long;
using VI = vector<int>; using VVI = vector<VI>; using VVVI = vector<VVI>;
using VL = vector<LL>; using VVL = vector<VL>; using VVVL = vector<VVL>;
using VB = vector<bool>; using VVB = vector<VB>; using VVVB = vector<VVB>;
using VD = vector<double>; using VVD = vector<VD>; using VVVD = vector<VVD>;
using VC = vector<char>; using VS = vector<string>; using VVC = vector<VC>;
using PII = pair<int,int>; using PLL = pair<LL,LL>; using PDD = pair<double,double>; using PIL = pair<int,LL>;
using MII = map<int,int>; using MLL = map<LL,LL>;
using SI = set<int>; using SL = set<LL>;
using MSI = multiset<int>; using MSL = multiset<LL>;
template<class T> using MAXPQ = priority_queue<T>;
template<class T> using MINPQ = priority_queue< T, vector<T>, greater<T> >;

const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll INF = 1LL << 60;
#define PI  3.14159265358979323846

#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define EACH(e, v) for(auto &e : v)
#define RITR(it, v) for(auto it = (v).rbegin(); it != (v).rend(); ++it)
#define ALL(v) v.begin(),v.end()

vector<ll> x8={1,1,1,0,0,-1,-1,-1},y8={1,0,-1,1,-1,1,0,-1};
int dx4[4]={1,-1,0,0}, dy4[4]={0,0,1,-1};

/*
memo
-uf,RMQ(segtree),BIT,BIT2,SegTree,SegTreeLazy
-isprime,Eratosthenes,gcdlcm,factorize,divisors,modpow,moddiv
nCr(+modnCr,inverse,extend_euclid.powmod),tobaseB,tobase10
-dijkstra,Floyd,bellmanford,sccd,topological,treediamiter
-compress1,compress2,rotate90

-co,ci,fo1,fo2,fo3,fo4
-bitsearch,binaryserach
-bfs
-SegTreedec,SegTreeLazydec
*/

long long gcd(long long a, long long b) {
    if (b == 0) {
        return a;
    } else {
        return gcd(b, a % b);
    }
}

long long lcm(long long a, long long b) {
    long long d = gcd(a, b);
    return a / d * b;
}

pair<long long,long long> crt(vector<long long> &b, vector<long long> &m){
    auto mod = [](long long a, long long m){return (a%m+m)%m;};
    auto extgcd = [] (long long a,long long b, long long &p, long long &q, auto extgcd){
        if(b==0){
            p = 1;q = 0;
            return a;
        }
        long long d = extgcd(b,a%b,q,p,extgcd);
        q -= a/b*p;
        return d;
    };

    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,extgcd);
        if((b[i]-r)%d != 0) return {0,-1};
        long long t = (b[i]-r) / d * p % (m[i]/d);
        r += M*t;
        M *= m[i]/d;
    }

    return {mod(r,M),M};
}

int main(){
    cin.tie(0);
    ios_base::sync_with_stdio(0);
    ll N = 3;
    VL a(N),b(N); for(ll i = 0; i < N; i++) cin >> a[i] >> b[i];

    PLL t = crt(a,b);
    if(t==PLL{0,-1}){
        cout << -1 << '\n';
    }
    else{
        ll ans = t.first;
        if(ans==0){
            ans = t.second;
        }
        cout << t.first << '\n';
    }
    
    
}