#pragma region Macros
#pragma GCC target("avx", "avx2")
#pragma GCC optimize("-O3", "unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#if __has_include(<atcoder/all>)
#include <atcoder/convolution>
#include <atcoder/fenwicktree>
#include <atcoder/lazysegtree>
// #include <atcoder/math>
#include <atcoder/maxflow>
#include <atcoder/mincostflow>
#include <atcoder/modint>
#include <atcoder/scc>
#include <atcoder/segtree>
#include <atcoder/string>
#include <atcoder/twosat>
using namespace atcoder;
#endif
using ll= long long;
using ld= long double;
using ull= unsigned long long;
using i128= __int128;
using pll= pair<ll, ll>;
using vi= vector<int>;
using vl= vector<ll>;
using vd= vector<ld>;
using vs= vector<string>;
using vi128= vector<i128>;
using vb= vector<bool>;
using vpll= vector<pll>;
using vvi= vector<vi>;
using vvl= vector<vl>;
using vvd= vector<vd>;
using vvs= vector<vs>;
using vvi128= vector<vi128>;
using vvb= vector<vb>;
using vvpll= vector<vpll>;
#if __has_include(<atcoder/all>)
using mint= modint1000000007;
// using mint = modint998244353;
#endif
constexpr ll mod= 1e9 + 7;
// constexpr ll mod= 998244353;
#define ALL(x) (x).begin(), (x).end()
#define _overload3(_1, _2, _3, name, ...) name
#define REPBASE(i, a, b) for(ll(i)= (a), (i##_b)= (b); (i) < (i##_b); (i)++)
#define RREPBASE(i, a, b) for(ll(i)= (a), (i##_b)= (b); (i) >= (i##_b); (i)--)
#define LOOP(n) REPBASE(i##__COUNTER__##_##__LINE__, 0, n)
#define REPB(i, n) REPBASE(i, 0, n)
#define REPS(i, n) REPBASE(i, 1, n + 1)
#define RREP(i, n) RREPBASE(i, n - 1, 0)
#define RREPS(i, n) RREPBASE(i, n, 1)
#define REP(...) _overload3(__VA_ARGS__, REPBASE, REPB, LOOP)(__VA_ARGS__)
#define EACH(x, c) for(auto &x : c)
#define PERM(p)   \
    sort(ALL(p)); \
    for(bool(p##c)= 1; (p##c); (p##c)= next_permutation(ALL(p)))
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
template <class T> inline ll SZ(const T &x) { return x.size(); }
ll TOPBIT(const ll &t) { return (t == 0 ? -1 : 63 - __builtin_clzll(t)); }
ll BIT(const ll &n) { return (1LL << n); }
template <class T> inline string YES(const T &n) { return (n ? "YES" : "NO"); }
template <class T> inline string Yes(const T &n) { return (n ? "Yes" : "No"); }
template <class T> inline string yes(const T &n) { return (n ? "yes" : "no"); }
template <class T> inline void UNIQUE(T &v) {
    v.erase(unique(ALL(v)), v.end());
}
template <class T, class U> inline ll LB(const T &v, const U &x) {
    return distance(v.begin(), lower_bound(ALL(v), x));
}
template <class T, class U> inline ll UB(const T &v, const U &x) {
    return distance(v.begin(), upper_bound(ALL(v), x));
}
template <class T> inline bool chmax(T &a, const T &b) {
    if(a < b) {
        a= b;
        return 1;
    }
    return 0;
}
template <class T> inline bool chmin(T &a, const T &b) {
    if(b < a) {
        a= b;
        return 1;
    }
    return 0;
}
const vpll dx4{{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
const vpll dx8{{1, 0},  {1, 1},   {0, 1},  {-1, 1},
               {-1, 0}, {-1, -1}, {0, -1}, {1, -1}};
#define VEC(name, size, ...)        \
    vector<__VA_ARGS__> name(size); \
    IN(name)
#define VV(name, h, w, ...)                                        \
    vector<vector<__VA_ARGS__>> name((h), vector<__VA_ARGS__>(w)); \
    IN(name)
#define LL(...)     \
    ll __VA_ARGS__; \
    IN(__VA_ARGS__)
#define STR(...)        \
    string __VA_ARGS__; \
    IN(__VA_ARGS__)
#define LD(...)     \
    ld __VA_ARGS__; \
    IN(__VA_ARGS__)
#define I128(...)     \
    i128 __VA_ARGS__; \
    IN(__VA_ARGS__)
void _scan() {}
template <class T, class S> void _scan(pair<T, S> &p) {
    _scan(p.fi), _scan(p.se);
}
template <class T> void _scan(T &a) { cin >> a; }
void IN() {}
template <class Head, class... Tail> void IN(Head &head, Tail &...tail) {
    _scan(head);
    IN(tail...);
}
template <class T> inline istream &operator>>(istream &stream, vector<T> &v) {
    EACH(x, v)
    stream >> x;
    return stream;
}
template <class T>
inline ostream &operator<<(ostream &stream, const vector<T> &v) {
    REP(i, SZ(v)) { stream << v[i] << (i == SZ(v) - 1 ? "" : " "); }
    return stream;
}
template <class T>
inline ostream &operator<<(ostream &stream, const vector<vector<T>> &v) {
    REP(i, SZ(v)) { stream << v[i] << (i == SZ(v) - 1 ? "" : "\n"); }
    return stream;
}
template <class T, class U>
inline istream &operator>>(istream &stream, pair<T, U> &p) {
    stream >> p.fi >> p.se;
    return stream;
}
template <class T, class U>
inline ostream &operator<<(ostream &stream, const pair<T, U> &p) {
    stream << p.fi << " " << p.se;
    return stream;
}
template <class T, class U>
inline pair<T, U> operator+(pair<T, U> p, const pair<T, U> &q) {
    p+= q;
    return p;
}
template <class T, class U>
inline pair<T, U> &operator+=(pair<T, U> &p, const pair<T, U> &q) {
    p.fi+= q.fi;
    p.se+= q.se;
    return p;
}
template <class T, class U>
inline pair<T, U> operator-(pair<T, U> p, const pair<T, U> &q) {
    p-= q;
    return p;
}
template <class T, class U>
inline pair<T, U> &operator-=(pair<T, U> &p, const pair<T, U> &q) {
    p.fi-= q.fi;
    p.se-= q.se;
    return p;
}
template <class T, class U> inline pair<T, U> operator+(const pair<T, U> &p) {
    return p;
}
template <class T, class U> inline pair<T, U> operator-(const pair<T, U> &p) {
    return mp(-p.fi, -p.se);
}
inline i128 parse(string &s) {
    reverse(ALL(s));
    i128 ret= 0;
    bool minus= 0;
    if(*(s.rbegin()) == '-') {
        minus= 1;
        s.pop_back();
    }
    while(!s.empty()) {
        if('0' <= *(s.rbegin()) && *(s.rbegin()) <= '9') {
            ret= ret * 10 + *(s.rbegin()) - '0';
            s.pop_back();
        } else {
            break;
        }
    }
    reverse(ALL(s));
    if(minus) ret*= -1;
    return ret;
}
inline string to_string(i128 val) {
    string ret= "";
    bool minus= 0;
    if(val < 0) {
        minus= 1;
        val*= -1;
    }
    do {
        int digit= val % 10;
        ret+= to_string(digit);
        val/= 10;
    } while(val != 0);
    if(minus) ret+= "-";
    reverse(ALL(ret));
    return ret;
}
inline istream &operator>>(istream &stream, i128 &val) {
    string str;
    stream >> str;
    val= parse(str);
    while(!str.empty()) {
        stream.putback(*(str.rbegin()));
        str.pop_back();
    }
    return stream;
}
inline ostream &operator<<(ostream &stream, const i128 &val) {
    stream << to_string(val);
    return stream;
}
inline void print() { cout << "\n"; }
template <class Head, class... Tail>
inline void print(const Head &H, const Tail &...T) {
    cout << H;
    (cout << ... << (cout << " ", T));
    cout << endl;
}
inline void debug_out() { cout << "\n"; }
template <class Head, class... Tail>
inline void debug_out(const Head &H, const Tail &...T) {
    cout << H;
    (cout << ... << (cout << " ", T));
    cout << endl;
}
#ifdef _DEBUG
#define debug(...) debug_out(__VA_ARGS__)
#else
#define debug(...)
#endif
#pragma endregion

/* safe_mod */
/* O(1) */
constexpr ll safe_mod(ll x, const ll &m= mod) {
    x%= m;
    if(x < 0) x+= m;
    return x;
}

pll crt(const vl &r, const vl &m) {
    ll r0= 0, m0= 1;
    REP(i, SZ(r)) {
        ll r1= safe_mod(r[i], m[i]), m1= m[i];
        if(m0 < m1) {
            swap(r0, r1);
            swap(m0, m1);
        }
        ll g= m1, t= m0 % m1, im= 0, im2= 1;
        if(t == 0) {
            if(r0 % m1 != r1) return {0, 0};
            continue;
        }
        while(t) {
            ll u= g / t;
            g-= t * u;
            im-= im2 * u;
            swap(g, t);
            swap(im, im2);
        }
        if(im < 0) im+= m1 / g;
        ll u1= m1 / g;
        ll s= (r1 - r0) / g;
        if(r1 - r0 - s * g) return {0, 0};
        ll x= s % u1 * im % u1;
        r0+= x * m0;
        m0*= u1;
        if(r0 < 0) r0+= m0;
    }
    return {r0, m0};
}

signed main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(12);
    vl X(3), Y(3);
    REP(i, 3) cin >> X[i] >> Y[i];
    auto [a, m]= crt(X, Y);
    if(m == 0) {
        print(-1);
    } else {
        if(a == 0) {
            print(m);
        } else {
            print(a);
        }
    }
}