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 Rust (1.42.0) (judge verdict: Accepted)

pub trait Zero: PartialEq + Sized {
    fn zero() -> Self;
    #[inline]
    fn is_zero(&self) -> bool {
        self == &Self::zero()
    }
}
pub trait One: PartialEq + Sized {
    fn one() -> Self;
    #[inline]
    fn is_one(&self) -> bool {
        self == &Self::one()
    }
}
macro_rules !zero_one_impls {($({$Trait :ident $method :ident $($t :ty ) *,$e :expr } ) *) =>{$($(impl $Trait for $t {#[inline ] fn $method () ->Self {$e } } ) *) *} ;}
zero_one_impls !({Zero zero u8 u16 u32 u64 usize i8 i16 i32 i64 isize u128 i128 ,0 } {Zero zero f32 f64 ,0. } {One one u8 u16 u32 u64 usize i8 i16 i32 i64 isize u128 i128 ,1 } {One one f32 f64 ,1. } ) ;
pub trait IterScan: Sized {
    type Output;
    fn scan<'a, I: Iterator<Item = &'a str>>(iter: &mut I) -> Option<Self::Output>;
}
pub trait MarkedIterScan: Sized {
    type Output;
    fn mscan<'a, I: Iterator<Item = &'a str>>(self, iter: &mut I) -> Option<Self::Output>;
}
#[derive(Clone, Debug)]
pub struct Scanner<'a> {
    iter: std::str::SplitAsciiWhitespace<'a>,
}
mod scanner_impls {
    use super::*;
    impl<'a> Scanner<'a> {
        #[inline]
        pub fn new(s: &'a str) -> Self {
            let iter = s.split_ascii_whitespace();
            Self { iter }
        }
        #[inline]
        pub fn scan<T: IterScan>(&mut self) -> <T as IterScan>::Output {
            <T as IterScan>::scan(&mut self.iter).expect("scan error")
        }
        #[inline]
        pub fn mscan<T: MarkedIterScan>(&mut self, marker: T) -> <T as MarkedIterScan>::Output {
            marker.mscan(&mut self.iter).expect("scan error")
        }
        #[inline]
        pub fn scan_vec<T: IterScan>(&mut self, size: usize) -> Vec<<T as IterScan>::Output> {
            (0..size)
                .map(|_| <T as IterScan>::scan(&mut self.iter).expect("scan error"))
                .collect()
        }
        #[inline]
        pub fn iter<'b, T: IterScan>(&'b mut self) -> ScannerIter<'a, 'b, T> {
            ScannerIter {
                inner: self,
                _marker: std::marker::PhantomData,
            }
        }
    }
    macro_rules !iter_scan_impls {($($t :ty ) *) =>{$(impl IterScan for $t {type Output =Self ;#[inline ] fn scan <'a ,I :Iterator <Item =&'a str >>(iter :&mut I ) ->Option <Self >{iter .next () ?.parse ::<$t >() .ok () } } ) *} ;}
    iter_scan_impls !(char u8 u16 u32 u64 usize i8 i16 i32 i64 isize f32 f64 u128 i128 String ) ;
    macro_rules !iter_scan_tuple_impl {($($T :ident ) *) =>{impl <$($T :IterScan ) ,*>IterScan for ($($T ,) *) {type Output =($(<$T as IterScan >::Output ,) *) ;#[inline ] fn scan <'a ,It :Iterator <Item =&'a str >>(_iter :&mut It ) ->Option <Self ::Output >{Some (($(<$T as IterScan >::scan (_iter ) ?,) *) ) } } } ;}
    iter_scan_tuple_impl!();
    iter_scan_tuple_impl!(A);
    iter_scan_tuple_impl !(A B ) ;
    iter_scan_tuple_impl !(A B C ) ;
    iter_scan_tuple_impl !(A B C D ) ;
    iter_scan_tuple_impl !(A B C D E ) ;
    iter_scan_tuple_impl !(A B C D E F ) ;
    iter_scan_tuple_impl !(A B C D E F G ) ;
    iter_scan_tuple_impl !(A B C D E F G H ) ;
    iter_scan_tuple_impl !(A B C D E F G H I ) ;
    iter_scan_tuple_impl !(A B C D E F G H I J ) ;
    iter_scan_tuple_impl !(A B C D E F G H I J K ) ;
    pub struct ScannerIter<'a, 'b, T> {
        inner: &'b mut Scanner<'a>,
        _marker: std::marker::PhantomData<fn() -> T>,
    }
    impl<'a, 'b, T: IterScan> Iterator for ScannerIter<'a, 'b, T> {
        type Item = <T as IterScan>::Output;
        #[inline]
        fn next(&mut self) -> Option<Self::Item> {
            <T as IterScan>::scan(&mut self.inner.iter)
        }
    }
}
pub mod marker {
    use super::*;
    use std::{iter::FromIterator, marker::PhantomData};
    #[derive(Debug, Copy, Clone)]
    pub struct Usize1;
    impl IterScan for Usize1 {
        type Output = usize;
        #[inline]
        fn scan<'a, I: Iterator<Item = &'a str>>(iter: &mut I) -> Option<Self::Output> {
            Some(<usize as IterScan>::scan(iter)?.checked_sub(1)?)
        }
    }
    #[derive(Debug, Copy, Clone)]
    pub struct Chars;
    impl IterScan for Chars {
        type Output = Vec<char>;
        #[inline]
        fn scan<'a, I: Iterator<Item = &'a str>>(iter: &mut I) -> Option<Self::Output> {
            Some(iter.next()?.chars().collect())
        }
    }
    #[derive(Debug, Copy, Clone)]
    pub struct CharsWithBase(pub char);
    impl MarkedIterScan for CharsWithBase {
        type Output = Vec<usize>;
        #[inline]
        fn mscan<'a, I: Iterator<Item = &'a str>>(self, iter: &mut I) -> Option<Self::Output> {
            Some(
                iter.next()?
                    .chars()
                    .map(|c| (c as u8 - self.0 as u8) as usize)
                    .collect(),
            )
        }
    }
    #[derive(Debug, Copy, Clone)]
    pub struct Collect<T: IterScan, B: FromIterator<<T as IterScan>::Output>> {
        size: usize,
        _marker: PhantomData<fn() -> (T, B)>,
    }
    impl<T: IterScan, B: FromIterator<<T as IterScan>::Output>> Collect<T, B> {
        pub fn new(size: usize) -> Self {
            Self {
                size,
                _marker: PhantomData,
            }
        }
    }
    impl<T: IterScan, B: FromIterator<<T as IterScan>::Output>> MarkedIterScan for Collect<T, B> {
        type Output = B;
        #[inline]
        fn mscan<'a, I: Iterator<Item = &'a str>>(self, iter: &mut I) -> Option<Self::Output> {
            Some(
                (0..self.size)
                    .map(|_| <T as IterScan>::scan(iter).expect("scan error"))
                    .collect::<B>(),
            )
        }
    }
}
#[macro_export]
macro_rules !min {($e :expr ) =>{$e } ;($e :expr ,$($es :expr ) ,+) =>{std ::cmp ::min ($e ,min !($($es ) ,+) ) } ;}
#[macro_export]
macro_rules !chmin {($dst :expr ,$($src :expr ) ,+) =>{{let x =std ::cmp ::min ($dst ,min !($($src ) ,+) ) ;$dst =x ;} } ;}
#[macro_export]
macro_rules !max {($e :expr ) =>{$e } ;($e :expr ,$($es :expr ) ,+) =>{std ::cmp ::max ($e ,max !($($es ) ,+) ) } ;}
#[macro_export]
macro_rules !chmax {($dst :expr ,$($src :expr ) ,+) =>{{let x =std ::cmp ::max ($dst ,max !($($src ) ,+) ) ;$dst =x ;} } ;}
pub trait Modulus {
    fn get_modulus() -> u32;
    #[inline]
    fn modulo(x: u32) -> u32 {
        x % Self::get_modulus()
    }
}
#[allow(unused_macros)]
macro_rules! make_modulus {
    ($t :ident ,$e :expr ) => {
        pub struct $t {}
        impl Modulus for $t {
            #[inline]
            fn get_modulus() -> u32 {
                const MODULUS: u32 = $e;
                MODULUS
            }
        }
    };
}
#[allow(unused_macros)]
macro_rules! make_dynamic_modulus {
    ($t :ident ,$m :ident ,$e :expr ) => {
        pub struct $t {}
        static mut $m: u32 = $e;
        impl Modulus for $t {
            #[inline]
            fn get_modulus() -> u32 {
                unsafe { $m }
            }
        }
    };
}
pub mod modulus {
    use super::*;
    pub struct Modulo1000000007 {}
    impl Modulus for Modulo1000000007 {
        #[inline]
        fn get_modulus() -> u32 {
            const MODULUS: u32 = 1_000_000_007;
            MODULUS
        }
    }
    pub struct Modulo1000000009 {}
    impl Modulus for Modulo1000000009 {
        #[inline]
        fn get_modulus() -> u32 {
            const MODULUS: u32 = 1_000_000_009;
            MODULUS
        }
    }
    pub struct Modulo998244353 {}
    impl Modulus for Modulo998244353 {
        #[inline]
        fn get_modulus() -> u32 {
            const MODULUS: u32 = 998_244_353;
            MODULUS
        }
    }
    pub struct DynModulo {}
    static mut DYN_MODULUS: u32 = 1_000_000_007;
    impl Modulus for DynModulo {
        #[inline]
        fn get_modulus() -> u32 {
            unsafe { DYN_MODULUS }
        }
    }
    pub fn set_dyn_modulus(m: u32) {
        unsafe {
            DYN_MODULUS = m;
        }
    }
}
pub struct MInt<M>
where
    M: Modulus,
{
    x: u32,
    _marker: std::marker::PhantomData<fn() -> M>,
}
mod mint_impls {
    use super::*;
    use std::{
        cmp::Ordering,
        fmt::{self, Debug},
        hash::{Hash, Hasher},
        iter::{Product, Sum},
        marker::PhantomData,
        mem::swap,
        num::ParseIntError,
        ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign},
        str::FromStr,
    };
    impl<M: Modulus> MInt<M> {
        #[inline]
        pub fn new(x: u32) -> Self {
            Self {
                x: M::modulo(x),
                _marker: PhantomData,
            }
        }
        #[inline]
        pub fn new_unchecked(x: u32) -> Self {
            Self {
                x,
                _marker: PhantomData,
            }
        }
        #[inline]
        pub fn inner(self) -> u32 {
            self.x
        }
        #[inline]
        pub fn get_mod() -> u32 {
            M::get_modulus()
        }
        #[inline]
        pub fn pow(mut self, mut y: usize) -> Self {
            let mut x = Self::one();
            while y > 0 {
                if y & 1 == 1 {
                    x *= self;
                }
                self *= self;
                y >>= 1;
            }
            x
        }
        #[inline]
        /// only prime modulus
        pub fn inv(self) -> Self {
            let mut a = self.x;
            let (mut b, mut u, mut s) = (M::get_modulus(), 1, 0);
            let k = a.trailing_zeros();
            a >>= k;
            for _ in 0..k {
                if u & 1 == 1 {
                    u += M::get_modulus();
                }
                u /= 2;
            }
            while a != b {
                if b < a {
                    swap(&mut a, &mut b);
                    swap(&mut u, &mut s);
                }
                b -= a;
                if s < u {
                    s += M::get_modulus();
                }
                s -= u;
                let k = b.trailing_zeros();
                b >>= k;
                for _ in 0..k {
                    if s & 1 == 1 {
                        s += M::get_modulus();
                    }
                    s /= 2;
                }
            }
            Self::new_unchecked(s)
        }
    }
    impl<M: Modulus> Clone for MInt<M> {
        #[inline]
        fn clone(&self) -> Self {
            Self {
                x: Clone::clone(&self.x),
                _marker: PhantomData,
            }
        }
    }
    impl<M: Modulus> Copy for MInt<M> {}
    impl<M: Modulus> Debug for MInt<M> {
        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
            Debug::fmt(&self.x, f)
        }
    }
    impl<M: Modulus> Default for MInt<M> {
        #[inline]
        fn default() -> Self {
            Self::zero()
        }
    }
    impl<M: Modulus> PartialEq for MInt<M> {
        #[inline]
        fn eq(&self, other: &Self) -> bool {
            PartialEq::eq(&self.x, &other.x)
        }
    }
    impl<M: Modulus> PartialOrd for MInt<M> {
        #[inline]
        fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
            PartialOrd::partial_cmp(&self.x, &other.x)
        }
    }
    impl<M: Modulus> Eq for MInt<M> {}
    impl<M: Modulus> Ord for MInt<M> {
        #[inline]
        fn cmp(&self, other: &Self) -> Ordering {
            Ord::cmp(&self.x, &other.x)
        }
    }
    impl<M: Modulus> Hash for MInt<M> {
        #[inline]
        fn hash<H: Hasher>(&self, state: &mut H) {
            Hash::hash(&self.x, state)
        }
    }
    impl<M: Modulus> From<u32> for MInt<M> {
        #[inline]
        fn from(x: u32) -> Self {
            Self::new(x)
        }
    }
    impl<M: Modulus> From<u64> for MInt<M> {
        #[inline]
        fn from(x: u64) -> Self {
            Self::new_unchecked((x % M::get_modulus() as u64) as u32)
        }
    }
    impl<M: Modulus> From<usize> for MInt<M> {
        #[inline]
        fn from(x: usize) -> Self {
            Self::new_unchecked((x % M::get_modulus() as usize) as u32)
        }
    }
    impl<M: Modulus> From<i32> for MInt<M> {
        #[inline]
        fn from(x: i32) -> Self {
            let x = x % M::get_modulus() as i32;
            if x < 0 {
                Self::new_unchecked((x + M::get_modulus() as i32) as u32)
            } else {
                Self::new_unchecked(x as u32)
            }
        }
    }
    impl<M: Modulus> From<i64> for MInt<M> {
        #[inline]
        fn from(x: i64) -> Self {
            let x = x % M::get_modulus() as i64;
            if x < 0 {
                Self::new_unchecked((x + M::get_modulus() as i64) as u32)
            } else {
                Self::new_unchecked(x as u32)
            }
        }
    }
    impl<M: Modulus> From<isize> for MInt<M> {
        #[inline]
        fn from(x: isize) -> Self {
            let x = x % M::get_modulus() as isize;
            if x < 0 {
                Self::new_unchecked((x + M::get_modulus() as isize) as u32)
            } else {
                Self::new_unchecked(x as u32)
            }
        }
    }
    impl<M: Modulus> Add for MInt<M> {
        type Output = Self;
        #[inline]
        fn add(self, rhs: Self) -> Self::Output {
            let mut x = self.x + rhs.x;
            if x >= M::get_modulus() {
                x -= M::get_modulus();
            }
            Self::new_unchecked(x)
        }
    }
    impl<M: Modulus> Sub for MInt<M> {
        type Output = Self;
        #[inline]
        fn sub(self, rhs: Self) -> Self::Output {
            if self.x < rhs.x {
                Self::new_unchecked(self.x + M::get_modulus() - rhs.x)
            } else {
                Self::new_unchecked(self.x - rhs.x)
            }
        }
    }
    impl<M: Modulus> Mul for MInt<M> {
        type Output = Self;
        #[inline]
        fn mul(self, rhs: Self) -> Self::Output {
            Self::new_unchecked((self.x as u64 * rhs.x as u64 % M::get_modulus() as u64) as u32)
        }
    }
    impl<M: Modulus> Div for MInt<M> {
        type Output = Self;
        #[inline]
        fn div(self, rhs: Self) -> Self::Output {
            self * rhs.inv()
        }
    }
    impl<M: Modulus> Neg for MInt<M> {
        type Output = Self;
        #[inline]
        fn neg(self) -> Self::Output {
            if self.x == 0 {
                Self::zero()
            } else {
                Self::new_unchecked(M::get_modulus() - self.x)
            }
        }
    }
    impl<M: Modulus> Sum for MInt<M> {
        #[inline]
        fn sum<I: Iterator<Item = Self>>(iter: I) -> Self {
            iter.fold(Self::zero(), Add::add)
        }
    }
    impl<M: Modulus> Product for MInt<M> {
        #[inline]
        fn product<I: Iterator<Item = Self>>(iter: I) -> Self {
            iter.fold(Self::one(), Mul::mul)
        }
    }
    impl<'a, M: Modulus + 'a> Sum<&'a MInt<M>> for MInt<M> {
        #[inline]
        fn sum<I: Iterator<Item = &'a Self>>(iter: I) -> Self {
            iter.fold(Self::zero(), Add::add)
        }
    }
    impl<'a, M: Modulus + 'a> Product<&'a MInt<M>> for MInt<M> {
        #[inline]
        fn product<I: Iterator<Item = &'a Self>>(iter: I) -> Self {
            iter.fold(Self::one(), Mul::mul)
        }
    }
    impl<M: Modulus> fmt::Display for MInt<M> {
        fn fmt<'a>(&self, f: &mut fmt::Formatter<'a>) -> Result<(), fmt::Error> {
            write!(f, "{}", self.x)
        }
    }
    impl<M: Modulus> FromStr for MInt<M> {
        type Err = ParseIntError;
        #[inline]
        fn from_str(s: &str) -> Result<Self, Self::Err> {
            s.parse::<u32>().map(Self::new)
        }
    }
    impl<M: Modulus> IterScan for MInt<M> {
        type Output = Self;
        #[inline]
        fn scan<'a, I: Iterator<Item = &'a str>>(iter: &mut I) -> Option<Self::Output> {
            iter.next()?.parse::<MInt<M>>().ok()
        }
    }
    impl<M: Modulus> Zero for MInt<M> {
        #[inline]
        fn zero() -> Self {
            Self::new_unchecked(0)
        }
    }
    impl<M: Modulus> One for MInt<M> {
        #[inline]
        fn one() -> Self {
            Self::new_unchecked(1)
        }
    }
    macro_rules! mint_ref_binop {
        ($imp :ident ,$method :ident ,$t :ty ) => {
            impl<M: Modulus> $imp<$t> for &$t {
                type Output = <$t as $imp<$t>>::Output;
                #[inline]
                fn $method(self, other: $t) -> <$t as $imp<$t>>::Output {
                    $imp::$method(*self, other)
                }
            }
            impl<M: Modulus> $imp<&$t> for $t {
                type Output = <$t as $imp<$t>>::Output;
                #[inline]
                fn $method(self, other: &$t) -> <$t as $imp<$t>>::Output {
                    $imp::$method(self, *other)
                }
            }
            impl<M: Modulus> $imp<&$t> for &$t {
                type Output = <$t as $imp<$t>>::Output;
                #[inline]
                fn $method(self, other: &$t) -> <$t as $imp<$t>>::Output {
                    $imp::$method(*self, *other)
                }
            }
        };
    }
    mint_ref_binop!(Add, add, MInt<M>);
    mint_ref_binop!(Sub, sub, MInt<M>);
    mint_ref_binop!(Mul, mul, MInt<M>);
    mint_ref_binop!(Div, div, MInt<M>);
    macro_rules! mint_ref_unop {
        ($imp :ident ,$method :ident ,$t :ty ) => {
            impl<M: Modulus> $imp for &$t {
                type Output = <$t as $imp>::Output;
                #[inline]
                fn $method(self) -> <$t as $imp>::Output {
                    $imp::$method(*self)
                }
            }
        };
    }
    mint_ref_unop!(Neg, neg, MInt<M>);
    macro_rules! mint_ref_op_assign {
        ($imp :ident ,$method :ident ,$t :ty ,$fromimp :ident ,$frommethod :ident ) => {
            impl<M: Modulus> $imp<$t> for $t {
                #[inline]
                fn $method(&mut self, rhs: $t) {
                    *self = $fromimp::$frommethod(*self, rhs);
                }
            }
            impl<M: Modulus> $imp<&$t> for $t {
                #[inline]
                fn $method(&mut self, other: &$t) {
                    $imp::$method(self, *other);
                }
            }
        };
    }
    mint_ref_op_assign!(AddAssign, add_assign, MInt<M>, Add, add);
    mint_ref_op_assign!(SubAssign, sub_assign, MInt<M>, Sub, sub);
    mint_ref_op_assign!(MulAssign, mul_assign, MInt<M>, Mul, mul);
    mint_ref_op_assign!(DivAssign, div_assign, MInt<M>, Div, div);
}
type M = MInt<modulus::Modulo1000000007>;
fn main() {
    #![allow(unused_imports, unused_macros)]
    use std::io::{stdin, stdout, BufWriter, Read as _, Write as _};
    let mut _in_buf = Vec::new();
    stdin().read_to_end(&mut _in_buf).expect("io error");
    let _in_buf = unsafe { String::from_utf8_unchecked(_in_buf) };
    let mut scanner = Scanner::new(&_in_buf);
    macro_rules !scan {() =>{scan !(usize ) } ;(($($t :tt ) ,*) ) =>{($(scan !($t ) ) ,*) } ;([$t :ty ;$len :expr ] ) =>{scanner .scan_vec ::<$t >($len ) } ;([$t :tt ;$len :expr ] ) =>{(0 ..$len ) .map (|_ |scan !($t ) ) .collect ::<Vec <_ >>() } ;([$t :ty ] ) =>{scanner .iter ::<$t >() } ;({$e :expr } ) =>{scanner .mscan ($e ) } ;($t :ty ) =>{scanner .scan ::<$t >() } ;}
    let _out = stdout();
    let mut _out = BufWriter::new(_out.lock());
    macro_rules !print {($($arg :tt ) *) =>(::std ::write !(_out ,$($arg ) *) .expect ("io error" ) ) }
    macro_rules !println {($($arg :tt ) *) =>(::std ::writeln !(_out ,$($arg ) *) .expect ("io error" ) ) }
    macro_rules! echo {
        ($iter :expr ) => {
            echo!($iter, '\n')
        };
        ($iter :expr ,$sep :expr ) => {
            let mut iter = $iter.into_iter();
            if let Some(item) = iter.next() {
                print!("{}", item);
            }
            for item in iter {
                print!("{}{}", $sep, item);
            }
            println!();
        };
    }
    let n = scan!();
    let ab = scan!([(i64, i64); n]);
    let ab: Vec<_> = ab.into_iter().filter(|t| *t != (0, 0)).collect();
    let k = M::from(n - ab.len());
    let az = ab.iter().filter(|t| t.0 == 0).count();
    let bz = ab.iter().filter(|t| t.1 == 0).count();
    let f = |n: usize| M::new(2).pow(n);
    let mut ans = f(az) + f(bz) - M::one();
    let ab: Vec<_> = ab.into_iter().filter(|t| t.0 != 0 && t.1 != 0).collect();
    let mp: Counter<_> = ab
        .iter()
        .map(|&(a, b)| {
            let g = gcd(a, b);
            let (a, b) = (a / g, b / g);
            (a * b.signum(), b * b.signum())
        })
        .collect();
    let mut used = std::collections::HashSet::new();
    for (t1, v) in mp.iter() {
        if used.contains(t1) {
            continue;
        }
        let t2 = (-t1.1 * t1.0.signum(), t1.0 * t1.0.signum());
        used.insert(*t1);
        used.insert(t2);
        let v2 = mp.get(&t2);
        ans *= f(*v) + f(v2) - M::one();
    }
    println!("{}", ans + k - M::one());
}
pub fn gcd(mut a: i64, mut b: i64) -> i64 {
    while b != 0 {
        a %= b;
        std::mem::swap(&mut a, &mut b);
    }
    a
}
#[derive(Clone, Debug)]
pub struct Counter<T: Eq + std::hash::Hash> {
    map: std::collections::HashMap<T, usize>,
}
impl<T: Eq + std::hash::Hash> Default for Counter<T> {
    #[inline]
    fn default() -> Self {
        Self {
            map: std::collections::HashMap::default(),
        }
    }
}
impl<T: Eq + std::hash::Hash> Counter<T> {
    #[inline]
    pub fn new() -> Self {
        Self::default()
    }
    #[inline]
    pub fn get(&self, key: &T) -> usize {
        self.map.get(key).cloned().unwrap_or_default()
    }
    #[inline]
    pub fn add(&mut self, key: T) {
        *self.map.entry(key).or_default() += 1usize;
    }
    #[inline]
    pub fn keys(&self) -> std::collections::hash_map::Keys<'_, T, usize> {
        self.map.keys()
    }
    #[inline]
    pub fn values(&self) -> std::collections::hash_map::Values<'_, T, usize> {
        self.map.values()
    }
    #[inline]
    pub fn iter(&self) -> std::collections::hash_map::Iter<'_, T, usize> {
        self.map.iter()
    }
}
impl<T: Eq + std::hash::Hash> std::iter::FromIterator<T> for Counter<T> {
    fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
        let mut map = Self::default();
        for key in iter {
            map.add(key);
        }
        map
    }
}