// to represent a cell in a spreadsheet
class Cell{
  int row;
  int col;
  IData data;
  
  Cell(int row, int col, IData data){
    this.row = row;
    this.col = col;
    this.data = data;
  }  
}

// to represent data in one cell of a spreadsheet
interface IData{
}

// to represent numerical data in one cell of a spreadsheet
class Number implements IData{
  int number;
  
  Number(int number){
    this.number = number;
  }
}

// to represent a formula in one cell of a spreadsheet
class Formula implements IData{
  Cell op1;
  Cell op2;
  IFun fun;
  
  Formula(Cell op1, Cell op2, IFun fun){
    this.op1 = op1;
    this.op2 = op2;
    this.fun = fun;
  }
}

// to represent a function of two arguments
interface IFun{
}

// to represent an addition function of two arguments
class Plus implements IFun{
}

// to represent a function of two arguments that produces the minimum
class Minimum implements IFun{
}

// to represent a multiplication function of two arguments
class Times implements IFun{
}