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 C# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Numerics;

namespace AtCoder.D
{
    public class Program
    {
        public static void Main() { var r = GetResult(); Debug.WriteLine(r); Console.Write(r); }

        /// <summary>
        /// ex) 4038333
        /// 4038 = (4038333 - 333) / 10^3
        /// 4038 * 10^3 = 4038333 - 333
        /// 4038 * 10^3 = (2 * 2019 + 333) - (0 * 2019 + 333)
        /// 4038 * 10^3 = (2 - 0) * 2019
        /// 10^n と 2019 は互いに素なので4038は2019の倍数
        /// </summary>
        private static object GetResult()
        {
            var S = ReadText();
            var countByMod = new long[2019];
            // 右端から考える
            S = new string(S.Reverse().ToArray());
            var currentMod = (Modular)0;
            for (int i = 0; i < S.Length; i++)
            {
                if (S[i] == '0') continue; // 問題の制約上、0は含まれない
                currentMod += int.Parse(S[i].ToString()) * Modular.Pow(10, i);
                countByMod[(int)currentMod]++;
            }

            var count = 0L;
            for (int i = 1; i < 2019; i++)
            {
                var n = countByMod[i];
                count += n * (n - 1) / 2;
            }

            // 割り切れた数値は純粋に足す
            count += countByMod[0];

            return count;
        }

        #region Console.Read

        public static string ReadText() { return Console.ReadLine(); }
        public static List<string> ReadTexts() { return Console.ReadLine().Split(' ').ToList(); }
        public static long ReadLong() { return long.Parse(Console.ReadLine()); }
        public static (long, long) Read2Longs() { var ls = ReadLongs(); return (ls[0], ls[1]); }
        public static (long, long, long) Read3Longs() { var ls = ReadLongs(); return (ls[0], ls[1], ls[2]); }
        public static (long, long, long, long) Read4Longs() { var ls = ReadLongs(); return (ls[0], ls[1], ls[2], ls[3]); }
        public static (long, long, long, long, long) Read5Longs() { var ls = ReadLongs(); return (ls[0], ls[1], ls[2], ls[3], ls[4]); }
        public static List<long> ReadLongs() { return Console.ReadLine().Split(' ').Select(x => long.Parse(x)).ToList(); }

        #endregion
    }
    public class Modular
    {
        public long Value { get; private set; }

        private static readonly long _mod = 2019;
        private static readonly List<int> _facCache = new List<int> { 1 };

        public static explicit operator long(Modular m)
        {
            return m.Value;
        }

        public static implicit operator Modular(long a)
        {
            var m = a % _mod;

            return new Modular
            {
                Value = (m < 0) ? m + _mod : m
            };
        }

        public static Modular operator +(Modular a, Modular b)
        {
            return a.Value + b.Value;
        }

        public static Modular operator -(Modular a, Modular b)
        {
            return a.Value - b.Value;
        }

        public static Modular operator *(Modular a, Modular b)
        {
            return a.Value * b.Value;
        }

        public static Modular operator /(Modular a, Modular b)
        {
            return a * Pow(b, _mod - 2);
        }

        public static Modular Pow(Modular a, long n)
        {
            switch (n)
            {
                case 0:
                    return 1;
                case 1:
                    return a;
                default:
                    var p = Pow(a, n / 2);
                    return p * p * Pow(a, n % 2);
            }
        }
        public static Modular Factorial(long n)
        {
            for (var i = _facCache.Count; i <= n; ++i)
            {
                var fac = (int)(Math.BigMul(_facCache.Last(), i) % _mod);
                _facCache.Add(fac);
            }
            return _facCache[(int)n];
        }
        public static Modular Combination(long n, long r)
        {
            Modular ans = 1;
            for (var i = 0; i < r; i++)
            {
                ans *= n - i;
            }
            for (var i = 1; i <= r; i++)
            {
                ans /= i;
            }

            return ans;
        }
        public override string ToString()
        {
            return Value.ToString();
        }
    }

}