Problem:
Score : 200 points

Problem Statement

You are given nonnegative integers a and b (a ≤ b), and a positive integer x.
Among the integers between a and b, inclusive, how many are divisible by x?

Constraints

0 ≤ a ≤ b ≤ 10^{18}

1 ≤ x ≤ 10^{18}

Input

The input is given from Standard Input in the following format:

a b x

Output

Print the number of the integers between a and b, inclusive, that are divisible by x.

Sample Input 1

4 8 2

Sample Output 1

3

There are three integers between 4 and 8, inclusive, that are divisible by 2: 4, 6 and 8.

Sample Input 2

0 5 1

Sample Output 2

6

There are six integers between 0 and 5, inclusive, that are divisible by 1: 0, 1, 2, 3, 4 and 5.

Sample Input 3

9 9 2

Sample Output 3

0

There are no integer between 9 and 9, inclusive, that is divisible by 2.

Sample Input 4

1 1000000000000000000 3

Sample Output 4

333333333333333333

Watch out for integer overflows.

Solution in C (GCC 9.2.1) (judge verdict: Time Limit Exceeded)

    #include<stdio.h>
    int main()
    {
        long long int a,b,c,d,e,count=0,i,n;
      scanf("%lld%lld%lld",&a,&b,&c);
      i=a;
     while(1){
        if(i%c==0){
            d=i;
            break;
        }
        i++;
     }
     i=b;
    while(1){
       if(i%c==0){
        e=i;
        break;
       }
       i++;
    }
    n=((e-d)/c)+1;
    if(e==b){
    printf("%lld",n);
    }else{
     printf("%lld",n-1);
    }

        return 0;
    }