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

using ll=long long;
#define int ll

#define rng(i,a,b) for(int i=int(a);i<int(b);i++)
#define rep(i,b) rng(i,0,b)
#define gnr(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define per(i,b) gnr(i,0,b)
#define pb push_back
#define eb emplace_back
#define a first
#define b second
#define bg begin()
#define ed end()
#define all(x) x.bg,x.ed
#define si(x) int(x.size())
#ifdef LOCAL
#define dmp(x) cerr<<__LINE__<<" "<<#x<<" "<<x<<endl
#else
#define dmp(x) void(0)
#endif

template<class t,class u> void chmax(t&a,u b){if(a<b)a=b;}
template<class t,class u> void chmin(t&a,u b){if(b<a)a=b;}

template<class t> using vc=vector<t>;
template<class t> using vvc=vc<vc<t>>;

using pi=pair<int,int>;
using vi=vc<int>;

template<class t,class u>
ostream& operator<<(ostream& os,const pair<t,u>& p){
	return os<<"{"<<p.a<<","<<p.b<<"}";
}

template<class t> ostream& operator<<(ostream& os,const vc<t>& v){
	os<<"{";
	for(auto e:v)os<<e<<",";
	return os<<"}";
}

#define mp make_pair
#define mt make_tuple
#define one(x) memset(x,-1,sizeof(x))
#define zero(x) memset(x,0,sizeof(x))
#ifdef LOCAL
void dmpr(ostream&os){os<<endl;}
template<class T,class... Args>
void dmpr(ostream&os,const T&t,const Args&... args){
	os<<t<<" ";
	dmpr(os,args...);
}
#define dmp2(...) dmpr(cerr,__LINE__,##__VA_ARGS__)
#else
#define dmp2(...) void(0)
#endif

using uint=unsigned;
using ull=unsigned long long;

template<class t,size_t n>
ostream& operator<<(ostream&os,const array<t,n>&a){
	return os<<vc<t>(all(a));
}

template<int i,class T>
void print_tuple(ostream&,const T&){
}

template<int i,class T,class H,class ...Args>
void print_tuple(ostream&os,const T&t){
	if(i)os<<",";
	os<<get<i>(t);
	print_tuple<i+1,T,Args...>(os,t);
}

template<class ...Args>
ostream& operator<<(ostream&os,const tuple<Args...>&t){
	os<<"{";
	print_tuple<0,tuple<Args...>,Args...>(os,t);
	return os<<"}";
}

template<class t>
void print(t x,int suc=1){
	cout<<x;
	if(suc==1)
		cout<<"\n";
	if(suc==2)
		cout<<" ";
}

ll read(){
	ll i;
	cin>>i;
	return i;
}

vi readvi(int n,int off=0){
	vi v(n);
	rep(i,n)v[i]=read()+off;
	return v;
}

template<class T>
void print(const vector<T>&v,int suc=1){
	rep(i,v.size())
		print(v[i],i==int(v.size())-1?suc:2);
}

string readString(){
	string s;
	cin>>s;
	return s;
}

template<class T>
T sq(const T& t){
	return t*t;
}

//#define CAPITAL
void yes(bool ex=true){
	#ifdef CAPITAL
	cout<<"YES"<<"\n";
	#else
	cout<<"Yes"<<"\n";
	#endif
	if(ex)exit(0);
}
void no(bool ex=true){
	#ifdef CAPITAL
	cout<<"NO"<<"\n";
	#else
	cout<<"No"<<"\n";
	#endif
	if(ex)exit(0);
}
void possible(bool ex=true){
	#ifdef CAPITAL
	cout<<"POSSIBLE"<<"\n";
	#else
	cout<<"Possible"<<"\n";
	#endif
	if(ex)exit(0);
}
void impossible(bool ex=true){
	#ifdef CAPITAL
	cout<<"IMPOSSIBLE"<<"\n";
	#else
	cout<<"Impossible"<<"\n";
	#endif
	if(ex)exit(0);
}

constexpr ll ten(int n){
	return n==0?1:ten(n-1)*10;
}

const ll infLL=LLONG_MAX/3;

#ifdef int
const int inf=infLL;
#else
const int inf=INT_MAX/2-100;
#endif

int topbit(signed t){
	return t==0?-1:31-__builtin_clz(t);
}
int topbit(ll t){
	return t==0?-1:63-__builtin_clzll(t);
}
int botbit(signed a){
	return a==0?32:__builtin_ctz(a);
}
int botbit(ll a){
	return a==0?64:__builtin_ctzll(a);
}
int popcount(signed t){
	return __builtin_popcount(t);
}
int popcount(ll t){
	return __builtin_popcountll(t);
}
bool ispow2(int i){
	return i&&(i&-i)==i;
}
int mask(int i){
	return (int(1)<<i)-1;
}

bool inc(int a,int b,int c){
	return a<=b&&b<=c;
}

template<class t> void mkuni(vc<t>&v){
	sort(all(v));
	v.erase(unique(all(v)),v.ed);
}

ll rand_int(ll l, ll r) { //[l, r]
	#ifdef LOCAL
	static mt19937_64 gen;
	#else
    static random_device rd;
    static mt19937_64 gen(rd());
    #endif
    return uniform_int_distribution<ll>(l, r)(gen);
}

template<class t>
int lwb(const vc<t>&v,const t&a){
	return lower_bound(all(v),a)-v.bg;
}

int gcd(int a,int b){return b?gcd(b,a%b):a;}

int extgcd(int a,int b,int&x,int&y){
	if(b==0){
		x=1;
		y=0;
		return a;
	}else{
		int g=extgcd(b,a%b,y,x);
		y-=a/b*x;
		return g;
	}
}

//x*y=g mod m
//returns (g,y)
pi modinv(int x,int m){
	int a,b;
	int g=extgcd(x,m,a,b);
	if(a<0)a+=m/g;
	return pi(g,a);
}

//x = a mod b
//x = c mod d
// => x = p mod q
//returns (-1,-1) when infeasible
pi crt(int a,int b,int c,int d){
	if(b<d){
		swap(a,c);
		swap(b,d);
	}
	c%=d;
	int g,e;
	tie(g,e)=modinv(b,d);
	int k=(c-a);
	if(k%g)return pi(-1,-1);
	k/=g;
	int m=b/g*d;
	int x=(a+k*e%(d/g)*b)%m;
	if(x<0)x+=m;
	return pi(x,m);
}

int garner(vc<pi> z,int m){
	int ans=0,w=1;
	rep(i,si(z)){
		int x=z[i].a;
		ans=(ans+w*x)%m;
		rng(j,i+1,si(z))
			z[j].a=(z[j].a+z[j].b-x%z[j].b)*modinv(z[i].b,z[j].b).b%z[j].b;
		w=(w*z[i].b)%m;
	}
	return ans;
}


template<class t>
t pow_mod(t x,t n,t m){
	t r=1;
	while(n){
		if(n&1)r=(r*x)%m;
		x=(x*x)%m;
		n>>=1;
	}
    return r;
}

bool is_prime(ll n) {
    if (n <= 1) return false;
    if (n == 2) return true;
    if (n % 2 == 0) return false;
    ll d = n - 1;
    while (d % 2 == 0) d /= 2;
    for (ll a : {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37}) {
        if (n <= a) break;
        ll t = d;
        ll y = pow_mod<__int128_t>(a, t, n);  // over
        while (t != n - 1 && y != 1 && y != n - 1) {
            y = __int128_t(y) * y % n;  // flow
            t <<= 1;
        }
        if (y != n - 1 && t % 2 == 0) {
            return false;
        }
    }
    return true;
}

ll pollard_single(ll n) {
    auto f = [&](ll x) { return (__int128_t(x) * x + 1) % n; };
    if (is_prime(n)) return n;
    if (n % 2 == 0) return 2;
    ll st = 0;
    while (true) {
        st++;
        ll x = st, y = f(x);
        while (true) {
            ll p = gcd((y - x + n), n);
            if (p == 0 || p == n) break;
            if (p != 1) return p;
            x = f(x);
            y = f(f(y));
        }
    }
}

vc<ll> pollard(ll n) {
    if (n == 1) return {};
    ll x = pollard_single(n);
    if (x == n) return {x};
    vc<ll> le = pollard(x);
    vc<ll> ri = pollard(n / x);
    le.insert(le.end(), ri.begin(), ri.end());
    return le;
}

signed main(){
	cin.tie(0);
	ios::sync_with_stdio(0);
	cout<<fixed<<setprecision(20);
	
	int n;cin>>n;
	vc<pi> q;
	rep(i,n){
		int a,b;cin>>a>>b;
		vi f=pollard(b);
		dmp(f);
		map<int,int> vs;
		for(auto v:f){
			if(vs.count(v)==0)vs[v]=1;
			vs[v]*=v;
		}
		for(auto kv:vs)
			q.eb(a%kv.b,kv.b);
	}
	sort(all(q),[](pi a,pi b){return a.b>b.b;});
	dmp(q);
	vc<pi> z;
	for(auto p:q){
		int a,b;tie(a,b)=p;
		bool found=false;
		for(auto&e:z){
			int c,d;tie(c,d)=e;
			int g=gcd(b,d);
			if(g>1){
				e=crt(a,b,c,d);
				if(e.a==-1){
					print(-1);
					return 0;
				}
				found=true;
				break;
			}
		}
		if(!found)z.eb(a,b);
	}
	
	int ans=garner(z,1000000007);
	cout<<ans<<endl;
}