#include <iostream>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>	// require sort next_permutation count __gcd reverse etc.
#include <cstdlib>	// require abs exit atof atoi 
#include <cstdio>		// require scanf printf
#include <functional>
#include <numeric>	// require accumulate
#include <cmath>		// require fabs
#include <climits>
#include <limits>
#include <cfloat>
#include <iomanip>	// require setw
#include <sstream>	// require stringstream 
#include <cstring>	// require memset
#include <cctype>		// require tolower, toupper
#include <fstream>	// require freopen
#include <ctime>		// require srand
#define rep(i,n) for(int i=0;i<(n);i++)
#define ALL(A) A.begin(), A.end()
#define EPS 1e-8

using namespace std;

typedef long long ll;
typedef pair<int, int> P;

int main()
{
	ios_base::sync_with_stdio(0);
	int a, b, x, y; cin >> a >> b >> x >> y;
	int g = __gcd (a, b );
	a /= g;
	b /= g;

	int ans = 0;
	for (int x3 = 1; x3 <= x; x3++ ){
		for (int y3 = 1; y3 <= y; y3++ ){
			if (b*x3 == a*y3 ){
				ans = max (ans, x3 + y3 );
			} // end if
		} // end for
	} // end for

	double ans1 = 0., ans2 = 0.;
	if ((double)(a*y)/(double)b <= (double)x ){
		ans1 = (double)(a*y)/(double)b + (double)y;
	} // end if
	if ((double)(b*x)/(double)a <= (double)y ){
		ans2 = (double)(b*x)/(double)a + (double)x;
	} // end if
	double res = (double)ans;
	res = max (res, ans1 );
	res = max (res, ans2 );
	printf ("%.9lf\n", (double)res  );
  
	return 0;
}