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

#define UNTIE ios_base::sync_with_stdio( false ); cin.tie( nullptr ) 
#define CIN( LL , A ) LL A; cin >> A 
#define ASSERT( A , MIN , MAX ) assert( MIN <= A && A <= MAX ) 
#define CIN_ASSERT( LL , A , MIN , MAX ) CIN( LL , A ); ASSERT( A , MIN , MAX ) 
#define TYPE_OF( VAR ) remove_const<remove_reference<decltype( VAR )>::type >::type
#define FOR( VAR , INITIAL , FINAL_PLUS_ONE ) for( TYPE_OF( FINAL_PLUS_ONE ) VAR = INITIAL ; VAR < FINAL_PLUS_ONE ; VAR ++ ) 
#define FOREQ( VAR , INITIAL , FINAL ) for( TYPE_OF( FINAL ) VAR = INITIAL ; VAR <= FINAL ; VAR ++ )  
#define REPEAT( HOW_MANY_TIMES ) FOR( VARIABLE_FOR_REPEAT , 0 , HOW_MANY_TIMES ) 
#define QUIT return 0 
#define RETURN( ANSWER ) cout << ( ANSWER ) << "\n"; QUIT 
#define DOUBLE( PRECISION , ANSWER ) cout << fixed << setprecision( PRECISION ) << ( ANSWER ) << endl; QUIT 

int main()
{
  UNTIE;
  CIN_ASSERT( int , A , 1 , 1000 );
  CIN_ASSERT( int , B , 1 , 1000 );
  CIN_ASSERT( int , X , 1 , 1000 );
  CIN_ASSERT( int , Y , 1 , 1000 );
  DOUBLE( 7 , ( X * B < Y * A ? ( ( X * ( A + B ) ) * 1.0 ) / A : ( ( Y * ( A + B ) ) * 1.0 ) / B ) );
}