Problem:
Score : 600 points

Problem Statement

There is an arithmetic progression with L terms: s_0, s_1, s_2, ... , s_{L-1}.

The initial term is A, and the common difference is B. That is, s_i = A + B \times i holds.

Consider the integer obtained by concatenating the terms written in base ten without leading zeros. For example, the sequence 3, 7, 11, 15, 19 would be concatenated into 37111519. What is the remainder when that integer is divided by M?

Constraints

All values in input are integers.

1 \leq L, A, B < 10^{18}

2 \leq M \leq 10^9

All terms in the arithmetic progression are less than 10^{18}.

Input

Input is given from Standard Input in the following format:

L A B M

Output

Print the remainder when the integer obtained by concatenating the terms is divided by M.

Sample Input 1

5 3 4 10007

Sample Output 1

5563

Our arithmetic progression is 3, 7, 11, 15, 19, so the answer is 37111519 mod 10007, that is, 5563.

Sample Input 2

4 8 1 1000000

Sample Output 2

891011

Sample Input 3

107 10000000000007 1000000000000007 998244353

Sample Output 3

39122908

Solution in Rust (1.42.0) (judge verdict: Accepted)

// ---------- begin ModInt ----------
mod modint {

    #[allow(dead_code)]
    pub struct Mod;
    impl ConstantModulo for Mod {
        const MOD: u32 = 1_000_000_007;
    }

    #[allow(dead_code)]
    pub struct StaticMod;
    static mut STATIC_MOD: u32 = 0;
    impl Modulo for StaticMod {
        fn modulo() -> u32 {
            unsafe { STATIC_MOD }
        }
    }

    #[allow(dead_code)]
    impl StaticMod {
        pub fn set_modulo(p: u32) {
            unsafe {
                STATIC_MOD = p;
            }
        }
    }

    use std::marker::*;
    use std::ops::*;

    pub trait Modulo {
        fn modulo() -> u32;
    }

    pub trait ConstantModulo {
        const MOD: u32;
    }

    impl<T> Modulo for T
    where
        T: ConstantModulo,
    {
        fn modulo() -> u32 {
            T::MOD
        }
    }

    pub struct ModInt<T>(pub u32, PhantomData<T>);

    impl<T> Clone for ModInt<T> {
        fn clone(&self) -> Self {
            ModInt::new_unchecked(self.0)
        }
    }

    impl<T> Copy for ModInt<T> {}

    impl<T: Modulo> Add for ModInt<T> {
        type Output = ModInt<T>;
        fn add(self, rhs: Self) -> Self::Output {
            let mut d = self.0 + rhs.0;
            if d >= T::modulo() {
                d -= T::modulo();
            }
            ModInt::new_unchecked(d)
        }
    }

    impl<T: Modulo> AddAssign for ModInt<T> {
        fn add_assign(&mut self, rhs: Self) {
            *self = *self + rhs;
        }
    }

    impl<T: Modulo> Sub for ModInt<T> {
        type Output = ModInt<T>;
        fn sub(self, rhs: Self) -> Self::Output {
            let mut d = T::modulo() + self.0 - rhs.0;
            if d >= T::modulo() {
                d -= T::modulo();
            }
            ModInt::new_unchecked(d)
        }
    }

    impl<T: Modulo> SubAssign for ModInt<T> {
        fn sub_assign(&mut self, rhs: Self) {
            *self = *self - rhs;
        }
    }

    impl<T: Modulo> Mul for ModInt<T> {
        type Output = ModInt<T>;
        fn mul(self, rhs: Self) -> Self::Output {
            let v = self.0 as u64 * rhs.0 as u64 % T::modulo() as u64;
            ModInt::new_unchecked(v as u32)
        }
    }

    impl<T: Modulo> MulAssign for ModInt<T> {
        fn mul_assign(&mut self, rhs: Self) {
            *self = *self * rhs;
        }
    }

    impl<T: Modulo> Neg for ModInt<T> {
        type Output = ModInt<T>;
        fn neg(self) -> Self::Output {
            if self.0 == 0 {
                Self::zero()
            } else {
                Self::new_unchecked(T::modulo() - self.0)
            }
        }
    }

    impl<T> std::fmt::Display for ModInt<T> {
        fn fmt<'a>(&self, f: &mut std::fmt::Formatter<'a>) -> std::fmt::Result {
            write!(f, "{}", self.0)
        }
    }

    impl<T: Modulo> std::str::FromStr for ModInt<T> {
        type Err = std::num::ParseIntError;
        fn from_str(s: &str) -> Result<Self, Self::Err> {
            let val = s.parse::<u32>()?;
            Ok(ModInt::new(val))
        }
    }

    impl<T: Modulo> From<usize> for ModInt<T> {
        fn from(val: usize) -> ModInt<T> {
            ModInt::new_unchecked((val % T::modulo() as usize) as u32)
        }
    }

    impl<T: Modulo> From<u64> for ModInt<T> {
        fn from(val: u64) -> ModInt<T> {
            ModInt::new_unchecked((val % T::modulo() as u64) as u32)
        }
    }

    impl<T: Modulo> From<i64> for ModInt<T> {
        fn from(val: i64) -> ModInt<T> {
            let m = T::modulo() as i64;
            ModInt::new((val % m + m) as u32)
        }
    }

    #[allow(dead_code)]
    impl<T> ModInt<T> {
        pub fn new_unchecked(d: u32) -> Self {
            ModInt(d, PhantomData)
        }
        pub fn zero() -> Self {
            ModInt::new_unchecked(0)
        }
        pub fn one() -> Self {
            ModInt::new_unchecked(1)
        }
        pub fn is_zero(&self) -> bool {
            self.0 == 0
        }
    }

    #[allow(dead_code)]
    impl<T: Modulo> ModInt<T> {
        pub fn new(d: u32) -> Self {
            ModInt::new_unchecked(d % T::modulo())
        }
        pub fn pow(&self, mut n: u64) -> Self {
            let mut t = Self::one();
            let mut s = *self;
            while n > 0 {
                if n & 1 == 1 {
                    t *= s;
                }
                s *= s;
                n >>= 1;
            }
            t
        }
        pub fn inv(&self) -> Self {
            assert!(self.0 != 0);
            self.pow(T::modulo() as u64 - 2)
        }
    }

    #[allow(dead_code)]
    pub fn mod_pow(r: u64, mut n: u64, m: u64) -> u64 {
        let mut t = 1 % m;
        let mut s = r % m;
        while n > 0 {
            if n & 1 == 1 {
                t = t * s % m;
            }
            s = s * s % m;
            n >>= 1;
        }
        t
    }
}
// ---------- end ModInt ----------
// ---------- begin Matrix ----------
#[allow(dead_code)]
mod matrix {
    use std::ops::{Add, Mul};
    pub trait SemiRing: Add<Output = Self> + Mul<Output = Self> + Copy {
        fn zero() -> Self;
        fn one() -> Self;
    }
    pub const SIZE: usize = 6;
    #[derive(Clone)]
    pub struct SquareMatrix<T: SemiRing> {
        buf: [[T; SIZE]; SIZE],
    }
    impl<T: SemiRing> SquareMatrix<T> {
        pub fn zero() -> Self {
            let z = T::zero();
            SquareMatrix {
                buf: [[z; SIZE]; SIZE],
            }
        }
        pub fn identity() -> Self {
            let mut m = Self::zero();
            for i in 0..SIZE {
                m.buf[i][i] = T::one();
            }
            m
        }
        pub fn set_at(&mut self, i: usize, j: usize, v: T) {
            self.buf[i][j] = v;
        }
        pub fn get_at(&self, i: usize, j: usize) -> T {
            self.buf[i][j]
        }
        pub fn matmul(&self, rhs: &Self) -> Self {
            let mut res = Self::zero();
            for (x, a) in res.buf.iter_mut().zip(self.buf.iter()) {
                for (a, b) in a.iter().zip(rhs.buf.iter()) {
                    for (x, b) in x.iter_mut().zip(b.iter()) {
                        *x = *x + *a * *b;
                    }
                }
            }
            res
        }
        pub fn matadd(&self, rhs: &Self) -> Self {
            let mut c = Self::zero();
            for (c, (a, b)) in c.buf.iter_mut().zip(self.buf.iter().zip(rhs.buf.iter())) {
                for (c, (a, b)) in c.iter_mut().zip(a.iter().zip(b.iter())) {
                    *c = *a + *b;
                }
            }
            c
        }
        pub fn matpow(&self, mut n: u64) -> Self {
            let mut t = Self::identity();
            let mut s = self.clone();
            while n > 0 {
                if n & 1 == 1 {
                    t = t.matmul(&s);
                }
                s = s.matmul(&s);
                n >>= 1;
            }
            t
        }
    }
}
// ---------- end Matrix ----------

use proconio::*;
use std::cmp::*;

use modint::*;
use matrix::*;

type M = ModInt<StaticMod>;
type Matrix = SquareMatrix<M>;

impl SemiRing for M {
    fn zero() -> Self {
        M::zero()
    }
    fn one() -> Self {
        M::one()
    }
}

fn run() {
    input! {
        mut l: u64,
        a: u64,
        b: u64,
        m: u32,
    }
    StaticMod::set_modulo(m);
    let mut s = a;
    let mut ans = Matrix::identity();
    while l > 0 {
        let mut d = 1;
        while 10u64.pow(d) <= s {
            d += 1;
        }
        let cnt = min(l, (10u64.pow(d) - s - 1) / b + 1);
        let mut mat = Matrix::identity();
        mat.set_at(0, 0, M::new(10).pow(d as u64));
        mat.set_at(1, 0, M::one());
        mat.set_at(2, 1, M::one());
        ans = ans.matmul(&mat.matpow(cnt));
        l -= cnt;
        s += cnt * b;
    }
    let ans = ans.get_at(1, 0) * M::from(a) + ans.get_at(2, 0) * M::from(b);
    println!("{}", ans);
}

fn main() {
    run();
}