597A - Divisibility - CodeForces Solution

#include <iostream>
#include <unordered_map>
#include <algorithm>
#include <vector>
#include <queue>
#include <unordered_set>
#include <cassert>
#include <unordered_map>
#include <math.h>
#include <iomanip>

typedef long long ll;

void solve() {
    ll k, a, b;
    std::cin >> k >> a >> b;

    ll first_num = a / k * k;
    if (first_num < a) {
        first_num += k;
    }

    ll last_num = b / k * k;
    if (last_num > b) {
        last_num -= k;
    }
    ll i = first_num / k;
    ll j = last_num / k;

    ll answer = j - i + 1;
    std::cout << answer << std::endl;
}

int main() {
    solve();
}