class TypeVar {

private String name;

public TypeVar(String nam){
name = nam;
}

public String getName(){
return name;
}

}





class MLType {

private TypeVar[][] expression;

public MLType(TypeVar[][] array){
    expression = new TypeVar[array.length][];
    for(int i = 0; i < array.length; i++){
        expression[i] = new TypeVar[array[i].length];
        for(int j = 0; j < array[i].length; j++){
            expression[i][j] = array[i][j];
        }
    }
}

public boolean findVar(TypeVar a){
    for(int i = 0; i<expression.length; i ++){
        for(int j = 0; i<expression[i].length; j++){
            expression[i][j] == a? return true : continue;
        }
    }
    return false;
}

public void mustNotDependOn(TypeVar a) throws ItDoesDependOn{
    findVar a? throw(new ItDoesDependOn) : return;
}

public String toString(){
    String rtrn = "";
    for(int i=0; i<expression.length; i++){
        if(expression[i].length == 1){
            rtrn += (expression[i].getName());
        }else{
            rtrn += "("
            for(int j=0; j<expression[i].length; j++){
                rtrn += (expression[i][j].getName());
                (j != expression[i].length - 1)? rtrn += "->":rtrn += ")";
            }
        }
        (i != expression.length - 1)?rtrn += "->":continue;
    }
}

}






class ItDoesDependOn extends Exception {

}






import java.util.List;
import java.util.LinkedList;

class Types {

private static List<TypeVar> types;

public static void main(String[] args){
types = new LinkedList<TypeVar>();
}

public static void createNewTypeVar(){
types.add(new TypeVar("t" + (types.size()+1)));
}

public static TypeVar getType(int n){
return types.get(n-1);
}

}