public static void main ( String [ ] args ) {
  Scanner in = new Scanner ( System . in ) ;
  int maxX = in . nextInt ( ) ;
  int maxY = in . nextInt ( ) ;
  int x = in . nextInt ( ) ;
  int y = in . nextInt ( ) ;
  int K = in . nextInt ( ) ;
  long answer = 0 ;
  for ( int k = 0 ;
  k < K ;
  k ++ ) {
    int dx = in . nextInt ( ) ;
    int dy = in . nextInt ( ) ;
    int xSpace = dx > 0 ? ( maxX - x ) : ( x - 1 ) ;
    int ySpace = dy > 0 ? ( maxY - y ) : ( y - 1 ) ;
    int steps = Integer . MAX_VALUE ;
    if ( dx != 0 ) {
      steps = Math . min ( steps , xSpace / Math . abs ( dx ) ) ;
    }
    if ( dy != 0 ) {
      steps = Math . min ( steps , ySpace / Math . abs ( dy ) ) ;
    }
    x += steps * dx ;
    y += steps * dy ;
    answer += steps ;
  }
  System . out . println ( answer ) ;
}

public static void main ( String [ ] args ) { Scanner in = new Scanner ( System . in ) ; int maxX = in . nextInt ( ) ; int maxY = in . nextInt ( ) ; int x = in . nextInt ( ) ; int y = in . nextInt ( ) ; int K = in . nextInt ( ) ; long answer = 0 ; for ( int k = 0 ; k < K ; k ++ ) { int dx = in . nextInt ( ) ; int dy = in . nextInt ( ) ; int xSpace = dx > 0 ? ( maxX - x ) : ( x - 1 ) ; int ySpace = dy > 0 ? ( maxY - y ) : ( y - 1 ) ; int steps = Integer . MAX_VALUE ; if ( dx != 0 ) { steps = Math . min ( steps , xSpace / Math . abs ( dx ) ) ; } if ( dy != 0 ) { steps = Math . min ( steps , ySpace / Math . abs ( dy ) ) ; } x += steps * dx ; y += steps * dy ; answer += steps ; } System . out . println ( answer ) ; }
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