Problem:
Score: 500 points

Problem Statement

We have caught N sardines. The deliciousness and fragrantness of the i-th sardine is A_i and B_i, respectively.

We will choose one or more of these sardines and put them into a cooler. However, two sardines on bad terms cannot be chosen at the same time.

The i-th and j-th sardines (i \neq j) are on bad terms if and only if A_i \cdot A_j + B_i \cdot B_j = 0.

In how many ways can we choose the set of sardines to put into the cooler? Since the count can be enormous, print it modulo 1000000007.

Constraints

All values in input are integers.

1 \leq N \leq 2 \times 10^5

-10^{18} \leq A_i, B_i \leq 10^{18}

Input

Input is given from Standard Input in the following format:

N
A_1 B_1
:
A_N B_N

Output

Print the count modulo 1000000007.

Sample Input 1

3
1 2
-1 1
2 -1

Sample Output 1

5

There are five ways to choose the set of sardines, as follows:

The 1-st

The 1-st and 2-nd

The 2-nd

The 2-nd and 3-rd

The 3-rd

Sample Input 2

10
3 2
3 2
-1 1
2 -1
-3 -9
-8 12
7 7
8 1
8 2
8 4

Sample Output 2

479

Solution in C# (Mono-csc 3.5.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Threading;
using System.Text;
using System.Text.RegularExpressions;
using System.Diagnostics;
using static util;
using P = pair<int, int>;

class Program {
    static void Main(string[] args) {
        var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
        var solver = new Solver(sw);
        // var t = new Thread(solver.solve, 1 << 26); // 64 MB
        // t.Start();
        // t.Join();
        solver.solve();
        sw.Flush();
    }
}

class Solver {
    StreamWriter sw;
    Scan sc;
    void Prt(string a) => sw.WriteLine(a);
    void Prt<T>(IEnumerable<T> a) => Prt(string.Join(" ", a));
    void Prt(params object[] a) => Prt(string.Join(" ", a));
    public Solver(StreamWriter sw) {
        this.sw = sw;
        this.sc = new Scan();
    }

    public void solve() {
        int n = sc.Int;
        var dic = new SortedDictionary<pair<long, long>, int>();
        int c = n;
        for (int i = 0; i < n; i++)
        {
            long a, b;
            sc.Multi(out a, out b);
            if (a == 0 && b == 0) {
                --c;
                continue;
            }
            long g = MyMath.gcd(Math.Abs(a), Math.Abs(b));
            a /= g;
            b /= g;
            if (a < 0 || a == 0 && b < 0) {
                a = -a;
                b = -b;
            }
            var p = new pair<long, long>(a, b);
            if (!dic.ContainsKey(p)) {
                dic.Add(p, 0);
            }
            ++dic[p];
        }
        long ans = MyMath.pow(2, c);
        foreach (var item in dic)
        {
            var p = new pair<long, long>(item.Key.v2, -item.Key.v1);
            if (p.v1 < 0 || p.v1 == 0 && p.v2 < 0) {
                p.v1 = -p.v1;
                p.v2 = -p.v2;
            }
            if (item.Key.CompareTo(p) < 0 && dic.ContainsKey(p)) {
                ans = ans * MyMath.inv(MyMath.pow(2, item.Value + dic[p])) % M * ((MyMath.pow(2, item.Value) + MyMath.pow(2, dic[p]) + M - 1) % M) % M;
            }
        }
        Prt((ans + M - 1) % M);
    }
}

class pair<T, U> : IComparable<pair<T, U>> {
    public T v1;
    public U v2;
    public pair() : this(default(T), default(U)) {}
    public pair(T v1, U v2) { this.v1 = v1; this.v2 = v2; }
    public int CompareTo(pair<T, U> a) {
        int c = Comparer<T>.Default.Compare(v1, a.v1);
        return c != 0 ? c : Comparer<U>.Default.Compare(v2, a.v2);
    }
    public override string ToString() => v1 + " " + v2;
    public void Deconstruct(out T a, out U b) { a = v1; b = v2; }
}
static class util {
    public static readonly int M = 1000000007;
    // public static readonly int M = 998244353;
    public static readonly long LM = 1L << 60;
    public static readonly double eps = 1e-11;
    public static void DBG(string a) => Console.Error.WriteLine(a);
    public static void DBG<T>(IEnumerable<T> a) => DBG(string.Join(" ", a));
    public static void DBG(params object[] a) => DBG(string.Join(" ", a));
    public static void Assert(params bool[] conds) {
        if (conds.Any(x => !x)) throw new Exception();
    }
    public static pair<T, U> make_pair<T, U>(T v1, U v2) => new pair<T, U>(v1, v2);
    public static int CompareList<T>(IList<T> a, IList<T> b) where T : IComparable<T> {
        for (int i = 0; i < a.Count && i < b.Count; i++)
            if (a[i].CompareTo(b[i]) != 0) return a[i].CompareTo(b[i]);
        return a.Count.CompareTo(b.Count);
    }
    public static bool inside(int i, int j, int h, int w) => i >= 0 && i < h && j >= 0 && j < w;
    static readonly int[] dd = { 0, 1, 0, -1 };
    // static readonly string dstring = "RDLU";
    public static P[] adjacents(int i, int j)
        => Enumerable.Range(0, dd.Length).Select(k => new P(i + dd[k], j + dd[k ^ 1])).ToArray();
    public static P[] adjacents(int i, int j, int h, int w)
        => Enumerable.Range(0, dd.Length).Select(k => new P(i + dd[k], j + dd[k ^ 1]))
                                         .Where(p => inside(p.v1, p.v2, h, w)).ToArray();
    public static P[] adjacents(this P p) => adjacents(p.v1, p.v2);
    public static P[] adjacents(this P p, int h, int w) => adjacents(p.v1, p.v2, h, w);
    public static Dictionary<T, int> compress<T>(this IEnumerable<T> a)
        => a.Distinct().OrderBy(v => v).Select((v, i) => new { v, i }).ToDictionary(p => p.v, p => p.i);
    public static Dictionary<T, int> compress<T>(params IEnumerable<T>[] a) => compress(a.Aggregate(Enumerable.Union));
    public static T[] inv<T>(this Dictionary<T, int> dic) {
        var res = new T[dic.Count];
        foreach (var item in dic) res[item.Value] = item.Key;
        return res;
    }
    public static void swap<T>(ref T a, ref T b) where T : struct { var t = a; a = b; b = t; }
    public static void swap<T>(this IList<T> a, int i, int j) where T : struct { var t = a[i]; a[i] = a[j]; a[j] = t; }
    public static T[] copy<T>(this IList<T> a) {
        var ret = new T[a.Count];
        for (int i = 0; i < a.Count; i++) ret[i] = a[i];
        return ret;
    }
    public static void Deconstruct<T>(this IList<T> v, out T a) {
        a = v[0];
    }
    public static void Deconstruct<T>(this IList<T> v, out T a, out T b) {
        a = v[0]; b = v[1];
    }
    public static void Deconstruct<T>(this IList<T> v, out T a, out T b, out T c) {
        a = v[0]; b = v[1]; c = v[2];
    }
    public static void Deconstruct<T>(this IList<T> v, out T a, out T b, out T c, out T d) {
        a = v[0]; b = v[1]; c = v[2]; d = v[3];
    }
    public static void Deconstruct<T>(this IList<T> v, out T a, out T b, out T c, out T d, out T e) {
        a = v[0]; b = v[1]; c = v[2]; d = v[3]; e = v[4];
    }
}

class Scan {
    StreamReader sr;
    public Scan() { sr = new StreamReader(Console.OpenStandardInput()); }
    public Scan(string path) { sr = new StreamReader(path); }
    public int Int => int.Parse(Str);
    public long Long => long.Parse(Str);
    public double Double => double.Parse(Str);
    public string Str => sr.ReadLine().Trim();
    public pair<T, U> Pair<T, U>() {
        T a; U b;
        Multi(out a, out b);
        return new pair<T, U>(a, b);
    }
    public P P => Pair<int, int>();
    public int[] IntArr => StrArr.Select(int.Parse).ToArray();
    public long[] LongArr => StrArr.Select(long.Parse).ToArray();
    public double[] DoubleArr => StrArr.Select(double.Parse).ToArray();
    public string[] StrArr => Str.Split(new[]{' '}, StringSplitOptions.RemoveEmptyEntries);
    bool eq<T, U>() => typeof(T).Equals(typeof(U));
    T ct<T, U>(U a) => (T)Convert.ChangeType(a, typeof(T));
    T cv<T>(string s) => eq<T, int>()    ? ct<T, int>(int.Parse(s))
                       : eq<T, long>()   ? ct<T, long>(long.Parse(s))
                       : eq<T, double>() ? ct<T, double>(double.Parse(s))
                       : eq<T, char>()   ? ct<T, char>(s[0])
                                         : ct<T, string>(s);
    public void Multi<T>(out T a) => a = cv<T>(Str);
    public void Multi<T, U>(out T a, out U b) {
        var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]);
    }
    public void Multi<T, U, V>(out T a, out U b, out V c) {
        var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]);
    }
    public void Multi<T, U, V, W>(out T a, out U b, out V c, out W d) {
        var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]); d = cv<W>(ar[3]);
    }
    public void Multi<T, U, V, W, X>(out T a, out U b, out V c, out W d, out X e) {
        var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]); d = cv<W>(ar[3]); e = cv<X>(ar[4]);
    }
}

static class MyMath {
    public static long Mod = util.M;
    // public static long Mod = 1000000007;
    public static bool isprime(long a) {
        if (a < 2) return false;
        for (long i = 2; i * i <= a; i++) if (a % i == 0) return false;
        return true;
    }
    public static bool[] sieve(int n) {
        var p = new bool[n + 1];
        for (int i = 2; i <= n; i++) p[i] = true;
        for (int i = 2; i * i <= n; i++) if (p[i]) for (int j = i * i; j <= n; j += i) p[j] = false;
        return p;
    }
    public static int[] sieve2(int n) {
        var p = new int[n + 1];
        for (int i = 2; i <= n; i++) p[i] = i;
        for (int i = 2; i * i <= n; i++) {
            if (p[i] == i)
                for (int j = i * i; j <= n; j += i)
                    p[j] = Math.Min(p[j], i);
        }
        return p;
    }
    public static bool[] segmentSieve(long l, long r) {
        int sqn = (int)Math.Sqrt(r + 9);
        var ps = getprimes(sqn);
        return segmentSieve(l, r,ps);
    }
    public static bool[] segmentSieve(long l, long r, List<int> ps) {
        var sieve = new bool[r - l + 1];
        for (long i = l; i <= r; i++) sieve[i - l] = true;
        foreach (long p in ps) {
            if (p * p > r) break;
            for (long i = p >= l ? p * p : (l + p - 1) / p * p; i <= r; i += p) sieve[i - l] = false;
        }
        return sieve;
    }
    public static List<int> getprimes(int n) {
        var prs = new List<int>();
        var p = sieve(n);
        for (int i = 2; i <= n; i++) if (p[i]) prs.Add(i);
        return prs;
    }
    public static long pow(long a, long b, long mod) {
        a %= mod;
        if (b < 0) Console.Error.WriteLine($"power number is negative ({a}^{b}).");
        if (b <= 0) return 1;
        var t = pow(a, b / 2, mod);
        if ((b & 1) == 0) return t * t % mod;
        return t * t % mod * a % mod;
    }
    public static long pow(long a, long b) => pow(a, b, Mod);
    public static long inv(long a) => pow(a, Mod - 2);
    public static long gcd(long a, long b) {
        while (b > 0) {
            var t = a % b;
            a = b;
            b = t;
        }
        return a;
    }
    // a x + b y = gcd(a, b)
    public static long extgcd(long a, long b, out long x, out long y) {
        long g = a; x = 1; y = 0;
        if (b > 0) { g = extgcd(b, a % b, out y, out x); y -= a / b * x; }
        return g;
    }

    // return (r, m): x = r (mod. m)
    // return (0, -1) if no answer
    public static pair<long, long> chineserem(IList<long> b, IList<long> m) {
        long r = 0, M = 1;
        for (int i = 0; i < b.Count; ++i) {
            long p, q;
            long d = extgcd(M, m[i], out p, out q); // p is inv of M/d (mod. m[i]/d)
            if ((b[i] - r) % d != 0) return new pair<long, long>(0, -1);
            long tmp = (b[i] - r) / d * p % (m[i]/d);
            r += M * tmp;
            M *= m[i]/d;
        }
        return new pair<long, long>((r % M + M) % M, M);
    }

    // return k: x^k = y (mod. mod) O(sqrt(mod))
    public static long modlog(long x, long y, long mod) {
        if (y == 1) return 0;
        long H = (long)Math.Sqrt(mod) + 1;
        var baby = new Dictionary<long, long>();
        for (long b = 0, xby = y; b < H; b++, xby = (xby * x) % mod) {
            if (!baby.ContainsKey(xby))
                baby.Add(xby, b);
            else
                baby[xby] = b;
        }

        long xH = 1;
        for (int i = 0; i < H; ++i) xH = xH * x % mod;
        for (long a = 1, xaH = xH; a <= H; a++, xaH = (xaH * xH) % mod)
            if (baby.ContainsKey(xaH))
                return a * H - baby[xaH];

        return -1;
    }
    public static long lcm(long a, long b) => a / gcd(a, b) * b;

    static long[] facts, invs;
    public static void setfacts(int n) {
        facts = new long[n + 1];
        facts[0] = 1;
        for (int i = 1; i <= n; i++) facts[i] = facts[i - 1] * i % Mod;
        invs = new long[n + 1];
        invs[n] = inv(facts[n]);
        for (int i = n; i > 0 ; i--) invs[i - 1] = invs[i] * i % Mod;
    }
    public static long fact(long n) {
        if (n < 0) return 0;
        if (facts != null && facts.Length > n) return facts[n];
        long numer = 1;
        for (long i = 1; i <= n; i++) numer = numer * (i % Mod) % Mod;
        return numer;
    }
    public static long perm(long n, long r) {
        if (n < 0 || r < 0 || r > n) return 0;
        if (facts != null && facts.Length > n) return facts[n] * invs[n - r] % Mod;
        long numer = 1;
        for (long i = 0; i < r; i++) numer = numer * ((n - i) % Mod) % Mod;
        return numer;
    }
    public static long comb(long n, long r) {
        if (n < 0 || r < 0 || r > n) return 0;
        if (facts != null && facts.Length > n) return facts[n] * invs[r] % Mod * invs[n - r] % Mod;
        if (n - r < r) r = n - r;
        long numer = 1, denom = 1;
        for (long i = 0; i < r; i++) {
            numer = numer * ((n - i) % Mod) % Mod;
            denom = denom * ((i + 1) % Mod) % Mod;
        }
        return numer * inv(denom) % Mod;
    }
    public static long multi_choose(long n, long r) => comb(n + r - 1, r);
    public static long[][] getcombs(int n) {
        var ret = new long[n + 1][];
        for (int i = 0; i <= n; i++) {
            ret[i] = new long[i + 1];
            ret[i][0] = ret[i][i] = 1;
            for (int j = 1; j < i; j++) ret[i][j] = (ret[i - 1][j - 1] + ret[i - 1][j]) % Mod;
        }
        return ret;
    }
    // nC0, nC2, ..., nCn
    public static long[] getcomb(int n) {
        var ret = new long[n + 1];
        ret[0] = 1;
        for (int i = 0; i < n; i++) ret[i + 1] = ret[i] * (n - i) % Mod * inv(i + 1) % Mod;
        return ret;
    }

    public static class ModMatrix {
        public static long[][] E(int n) {
            var ret = new long[n][];
            for (int i = 0; i < n; i++) { ret[i] = new long[n]; ret[i][i] = 1; }
            return ret;
        }
        public static long[][] pow(long[][] A, long n) {
            if (n == 0) return E(A.Length);
            var t = pow(A, n / 2);
            if ((n & 1) == 0) return mul(t, t);
            return mul(mul(t, t), A);
        }
        public static long dot(long[] x, long[] y) {
            int n = x.Length;
            long ret = 0;
            for (int i = 0; i < n; i++) ret = (ret + x[i] * y[i]) % Mod;
            return ret;
        }
        public static long[][] trans(long[][] A) {
            int n = A[0].Length, m = A.Length;
            var ret = new long[n][];
            for (int i = 0; i < n; i++) { ret[i] = new long[m]; for (int j = 0; j < m; j++) ret[i][j] = A[j][i]; }
            return ret;
        }
        public static long[] mul(long a, long[] x) {
            int n = x.Length;
            var ret = new long[n];
            for (int i = 0; i < n; i++) ret[i] = a * x[i] % Mod;
            return ret;
        }
        public static long[] mul(long[][] A, long[] x) {
            int n = A.Length;
            var ret = new long[n];
            for (int i = 0; i < n; i++) ret[i] = dot(x, A[i]);
            return ret;
        }
        public static long[][] mul(long a, long[][] A) {
            int n = A.Length;
            var ret = new long[n][];
            for (int i = 0; i < n; i++) ret[i] = mul(a, A[i]);
            return ret;
        }
        public static long[][] mul(long[][] A, long[][] B) {
            int n = A.Length;
            var Bt = trans(B);
            var ret = new long[n][];
            for (int i = 0; i < n; i++) ret[i] = mul(Bt, A[i]);
            return ret;
        }
    }
}