using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using static System.Console;
using static AtCoder.Util;
using static AtCoder.Cin;
using static System.Math;
namespace AtCoder {
class Program {
struct RangeEnd : IComparable<RangeEnd> {
public int Place;
public int T;
public RangeEnd(int place, int t) {
Place = place;
T = t;
}
public int CompareTo(RangeEnd other) =>
this.Place.CompareTo(other.Place);
}
static void Main() {
var a = ReadLong();
var b = ReadLong();
var x = ReadLong();
(a > 0 ? b / x - (a - 1) / x : b / x + 1).WriteLine();
}
}
}
/* ***************** Following Contents are my common library ******** */
namespace AtCoder {
static class Util {
public const long MODCONST = 1000000007;
public static T debug<T>(this T value) {
Console.Error.WriteLine($"debug:{value}");
return value;
}
public static long ToLong(this String s) => long.Parse(s);
public static long ToLong(this char c) => c - '0';
public static int ToInt(this String s) => int.Parse(s);
public static int ToInt(this char c) => c - '0';
public static void Times(this int n, Action action) {
for (int i = 0; i < n; i++) action();
}
public static void Times(this long n, Action action) {
for (long i = 0; i < n; i++) action();
}
public static void Call<T>(this T t, Action<T> action) => action(t);
public static bool In<T>(this T t, IEnumerable<T> range) =>
range.Contains(t);
public static void WriteLine<T>(this T t) => Console.WriteLine(t);
public static T Call<S, T>(this S s, Func<S, T> func) => func(s);
public static void Each<T>(this IEnumerable<T> e, Action<T> action) {
foreach (var v in e) action(v);
}
public static VectorInt2 ReadVectorInt2() =>
new VectorInt2(ReadInt(), ReadInt());
public static string ReplaceX(this string input, string pattern, string replace) =>
Regex.Replace(input, pattern, replace);
public static IEnumerable<int> Range(int i, int j) => Enumerable.Range(i, j);
public static void Swap<T>(this IList<T> enumerable, int i, int j) {
var buf = enumerable[i];
enumerable[i] = enumerable[j];
enumerable[j] = buf;
}
public static void ReverseRange<T>(this IList<T> enumerable, int i, int j) {
int half = (j - i) / 2;
for (int k = 0; k <= half; k++) enumerable.Swap(i + k, j - k);
}
public static bool isEmpty<T>(this IEnumerable<T> enumerable) => !enumerable.Any();
}
static class Cin {
private static Queue<string> tokens;
static Cin () {
string line;
tokens = new Queue<string> ();
while ((line = Console.ReadLine ()) != null) {
foreach (var token in line.Split (' ')) {
tokens.Enqueue (token);
}
}
}
static public int ReadInt() => int.Parse(tokens.Dequeue());
static public IEnumerable<int> ReadInt(long n) {
var list = new List<int>();
for (int i = 0; i < n; i++) list.Add(ReadInt());
return list;
}
static public long ReadLong() => long.Parse(tokens.Dequeue());
static public IEnumerable<long> ReadLong(long n) {
for (int i = 0; i < n; i++) yield return ReadLong();
}
static public string ReadString() => tokens.Dequeue();
static public IEnumerable<string> ReadString(long n) {
for (int i = 0; i < n; i++) yield return ReadString();
}
}
struct VectorInt2 {
public int X { get; set; }
public int Y { get; set; }
public VectorInt2(int x, int y) {
X = x; Y = y;
}
static public VectorInt2 operator+ (VectorInt2 v1, VectorInt2 v2) =>
new VectorInt2(v1.X + v2.X, v1.Y + v2.Y);
static public VectorInt2 operator- (VectorInt2 v1, VectorInt2 v2) =>
new VectorInt2(v1.X - v2.X, v1.Y - v2.Y);
static public VectorInt2 operator* (VectorInt2 v1, VectorInt2 v2) =>
new VectorInt2(v1.X * v2.X, v1.Y * v2.Y);
static public VectorInt2 operator* (VectorInt2 v1, int i) =>
new VectorInt2(v1.X * i, v1.Y * i);
static public VectorInt2 operator* (int i, VectorInt2 v2) =>
new VectorInt2(i * v2.X, i * v2.Y);
static public VectorInt2 operator/ (VectorInt2 v1, int i) =>
new VectorInt2(v1.X / i, v1.Y / i);
}
}