#include 

using namespace std;

int main()
{
    int p = 0;
    int denovi = 0;
    int m, d, n;
    cin >> m >> d >> n;
    while (p < m)
    {
        denovi++;
        p += d;
        if (p >= m)
        {
            cout << denovi << endl;
            break;
        }
        p -= n;
    }
    return 0;
}