#include <bits/stdc++.h>
using namespace std;

int main() {
	int a, b, c;
	cin >> a >> b >> c;
	cout << a - b *c;
	return 0;
}

#include <bits/stdc++.h> using namespace std;

//main int main() { int n, a, x; cin >> n >> a >> x; cout << n - a *x << endl;

return 0;

}