1

#include <iostream>

int main()
{
    int N, M, K;
    std::cin >> N >> K >> M;

    int count_substances = K - K % M;
    int count = 0;

    while (N >= K)
    {
        N -= count_substances;
        count++;
    }

    std::cout << count * (K / M) << std::endl;
    return 0;
}