#include <bits/stdc++.h>

#define int long long
#define double long double

using namespace std;

template <class T>
string tostr(T x) {
	stringstream o;
	o << x;
	return o.str();
}
template <class T>
T sqr(T x) { return x * x; }
template <class T>
T mypow(T x, int n) {
	T r = 1;
	while (n > 0) {
		if (n & 1) r = r * x;
		x = x * x;
		n >>= 1;
	}
	return r;
}

int toint(string s) {
	int v;
	stringstream i(s);
	i >> v;
	return v;
}
bool check(int x, int y, int w, int h) { return x >= 0 && y >= 0 && w > x && h > y; }
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
int lcm(int a, int b) { return a / gcd(a, b) * b; }

#define REP(i, a, b) for (int(i) = (a); i < (b); (i)++)
#define rep(i, n) REP(i, 0, n)
#define PER(i, a, b) for (int(i) = (a - 1); i >= (b); (i)--)
#define per(i, n) PER(i, n, 0)
#define each(i, n) for (auto &i : n)
#define clr(a) memset((a), 0, sizeof(a))
#define mclr(a) memset((a), -1, sizeof(a))
#define all(a) (a).begin(), (a).end()
#define dump(val) cerr << #val " = " << val << endl;
#define dum(val) cerr << #val " = " << val;
#define FILL(a, v) fill(a, a + sizeof(a) / sizeof(*a), v)

const int dx[8] = {+1, +0, -1, +0, +1, +1, -1, -1};
const int dy[8] = {+0, -1, +0, +1, -1, +1, -1, +1};
const int mod = 1e9 + 7;
const int INF = 1e9;

signed main() {
	double a, b, c;
	cin >> a >> b >> c;

	double d = (b * b - c * a) / (b - a);
	double r;

	if (b != 0) {
		r = (c - d) / b;
		if (r * c + d >= 0) {
			cout << signed(r * c + d + 0.999999999) << endl;
		} else {
			cout << signed(r * c + d - 0.999999999) << endl;
		}
		return 0;
	}
	if (a != 0) {
		r = (b - d) / a;
		if (r * c + d >= 0) {
			cout << signed(r * c + d + 0.999999999) << endl;
		} else {
			cout << signed(r * c + d - 0.999999999) << endl;
		}
		return 0;
	}
}