G_ACM_2

#include <iostream>
#include <cstdio>

using namespace std;

int main()
{
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);

    double s, d, n;
    cin >> s >> d >> n;

    double temp;

    if (d == 0) cout << "0\n";
    else
    {
        for (int i = 1; i <= 100; i++)
        {
            temp = s;
            for (int j = 0; j < n; j++)
            {
                temp = temp + (temp * i * 0.01);
            }
            if (temp == (s + d))
            {
                cout << i << endl;
                break;
            }
        }
    }
}