#include <bits/stdc++.h>
using namespace std;
int main()
{
    long long n,m,x;
    cin >> n >> m >> x;
    long long sum = 0;
    for (long long i = n;i <= m;i++)
    {
        if(i % x == 0)
        {
            sum++;
        }
    }
    cout << sum;
}

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