#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

long long ext_gcd(long long a, long long b, long long &x, long long &y){
    if(b == 0){ x = 1; y = 0; return a;}
    long long d = ext_gcd(b, a%b, y, x);
    y -= a / b * x;
    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 = ext_gcd(M, m[i], p, q);
        if((b[i] - r) % d != 0) return {0, -1};
        long long tmp = (b[i] - r) / d * p % (m[i] / d);
        r += M * tmp;
        M *= m[i] / d;
    }
    return {(r % M + M) % M, M};
}

long long modinv(long long a, long long m){
    long long x,y;
    ext_gcd(a, m, x, y);
    return (x % m + m) % m;
}

// x[i] \equiv b[i] (mod m[i])
long long Garner(vector<long long> b, vector<long long> m, long long MOD) {
    m.push_back(MOD);
    vector<long long> coeffs((int)m.size(), 1);
    vector<long long> consts((int)m.size(), 0);
    for(int k = 0; k < (int)b.size(); k++) {
        long long t = (b[k] - consts[k] + MOD) % MOD;
        t = (t * modinv(coeffs[k], m[k]))  % MOD;
        for(int i = k + 1; i < (int)m.size(); i++) {
            consts[i] = (consts[i] + t * coeffs[i] % MOD) % m[i];
            coeffs[i] = (coeffs[i] * m[k]) % m[i];
        }
    }
    return consts.back();
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    vector<ll> x(3), y(3);
    rep(i,3) cin >> x[i] >> y[i];
    pair<ll,ll> a = CRT(x, y);
    
    if(a.second == -1){
        cout << -1 << endl;
    }else{
        cout << (x[0] && x[1] && x[2] ? a.first : a.second) << endl;
    }
}