#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(auto& (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define cmx(x,y) x=max(x,y)
#define cmn(x,y) x=min(x,y)
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define sar(a,n) {cout<<#a<<":";rep(pachico,n)cout<<" "<<a[pachico];cout<<endl;}
#define int long long

using namespace std;

template<typename S,typename T>auto&operator<<(ostream&o,pair<S,T>p){return o<<"{"<<p.fi<<","<<p.se<<"}";}
template<typename T>auto&operator<<(ostream&o,set<T>s){for(auto&e:s)o<<e<<" ";return o;}
template<typename S,typename T,typename U>
auto&operator<<(ostream&o,priority_queue<S,T,U>q){while(!q.empty())o<<q.top()<<" ",q.pop();return o;}
template<typename K,typename T>auto&operator<<(ostream&o,map<K,T>&m){for(auto&e:m)o<<e<<" ";return o;}
template<typename T>auto&operator<<(ostream&o,vector<T>v){for(auto&e:v)o<<e<<" ";return o;}
void ashow(){cout<<endl;}template<typename T,typename...A>void ashow(T t,A...a){cout<<t<<" ";ashow(a...);}
template<typename S,typename T,typename U>
struct TRI{S fi;T se;U th;TRI(){}TRI(S f,T s,U t):fi(f),se(s),th(t){}
bool operator<(const TRI&_)const{return(fi==_.fi)?((se==_.se)?(th<_.th):(se<_.se)):(fi<_.fi);}};
template<typename S,typename T,typename U>
auto&operator<<(ostream&o,TRI<S,T,U>&t){return o<<"{"<<t.fi<<","<<t.se<<","<<t.th<<"}";}

typedef pair<int, int> P;
typedef pair<ll, ll> pll;
typedef TRI<int, int, int> tri;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<P> vp;
typedef vector<double> vd;
typedef vector<string> vs;

const int MAX_N = 32005;

template<typename T>
T mod_add(const T a, const T b, const T mod){
    return (a + b) % mod;
}

template<typename T>
T mod_mul(const T a, const T b, const T mod){
    return a * b % mod;
}

template<typename T>
T mod_pow(T a, T b, const T mod){
    T res = 1;
    while(b){
        if(b & 1){
            res = mod_mul(res, a, mod);
        }
        a = mod_mul(a, a, mod);
        b >>= 1;
    }
    return res;
}

template<typename T>
T mod_inv(T a, T mod){
    T u[] = {a, 1, 0}, v[] = {mod, 0, 1}, t;
    while(*v){
        t = *u / *v;
        swap(u[0] -= t * v[0], v[0]), swap(u[1] -= t * v[1], v[1]), swap(u[2] -= t * v[2], v[2]);
    }
    u[1] %= mod;
    return (u[1] < 0) ? (u[1] + mod) : u[1];
}

bool flag;

template<typename T>
T garner(const vector<T>& a, vector<T> p, const T mod){
    const unsigned int sz = a.size();
    vector<T> kp(sz + 1, 0), rmult(sz + 1, 1);
    p.push_back(mod);
    for(unsigned int i = 0; i < sz; ++i){
        T x = mod_mul(a[i] - kp[i], mod_inv(rmult[i], p[i]), p[i]);
        x = (x < 0) ? (x + p[i]) : x;
        for(unsigned int j = i + 1; j < sz + 1; ++j){
            kp[j] = mod_add(kp[j], rmult[j] * x, p[j]);
            rmult[j] = mod_mul(rmult[j], p[i], p[j]);
        }
    }
    if(flag) return rmult[sz];
    return kp[sz];
}

vector<int> prime;
bool is_prime[MAX_N];

void sieve(int n){
	for(int i=0;i<=n;i++){
		is_prime[i] = true;
	}
	is_prime[0] = is_prime[1] = false;
	for(int i=2;i<=n;i++){
		if(is_prime[i]){
			prime.push_back(i);
			for(int j=2*i;j<=n;j+=i){
				is_prime[j] = false;
			}
		}
	}
}

signed main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    sieve(32000);
    map<int, vp> mp;
    flag = true;
    rep(i,n){
        int x, y;
        cin >> x >> y;
        if(x) flag = false;
        for(int p : prime){
            if(y % p) continue;
            int mult = 1;
            do{
                y /= p, mult *= p;
            }while(y % p == 0);
            mp[p].emplace_back(x % mult, mult);
        }
        if(y > 1) mp[y].emplace_back(x % y, y);
    }
    vl x, y;
    for(const auto& it : mp){
        int a = 0, b = 0;
        for(const P& p : it.se){
            if(a < p.se) a = p.se, b = p.fi;
        }
        for(const P& p : it.se){
            if(p.fi != b % p.se){
                cout << "-1\n";
                return 0;
            }
        }
        x.pb(b), y.pb(a);
    }
    cout << garner(x, y, (long long)MOD) << "\n";
    return 0;
}