Problem:
Score : 400 points

Problem Statement

Given is a string S consisting of digits from 1 through 9.

Find the number of pairs of integers (i,j) (1 ≤ i ≤ j ≤ |S|) that satisfy the following condition:

Condition: In base ten, the i-th through j-th characters of S form an integer that is a multiple of 2019.

Constraints

1 ≤ |S| ≤ 200000

S is a string consisting of digits from 1 through 9.

Input

Input is given from Standard Input in the following format:

S

Output

Print the number of pairs of integers (i,j) (1 ≤ i ≤ j ≤ |S|) that satisfy the condition.

Sample Input 1

1817181712114

Sample Output 1

3

Three pairs - (1,5), (5,9), and (9,13) - satisfy the condition.

Sample Input 2

14282668646

Sample Output 2

2

Sample Input 3

2119

Sample Output 3

0

No pairs satisfy the condition.

Solution in Go (1.14.1) (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
)

func scanText() string {
	sc.Buffer([]byte{}, math.MaxInt64)
	sc.Scan()
	return sc.Text()
}

func reverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}
	return string(runes)
}

var sc = bufio.NewScanner(os.Stdin)

func main() {
	N := 2019
	s := reverse(scanText())
	m := map[int]int{}
	total := 0
	d := 1
	m[0] = 1
	for _, c := range s {
		n, _ := strconv.Atoi(string(c))
		total += n * d
		total %= 2019
		d = (d * 10) % N
		m[total]++
	}
	sum := 0
	for _, v := range m {
		sum += v * (v - 1) / 2
	}
	fmt.Println(sum)
}