Students are sitting in a row in which the position of X is 17th from the left and that of Y is 14th from the right. If they interchange their positions, X's position becomes 7th from the left. How many students are there in the row?
If each term in the given sequence is assigned number 1, 2, 3... according to their position from the left, then the sum of the numerical values of the positions of the symbols will be ____.