The number of ways in which 20 letters <img alt="\mathrm{x_{1}, x_{2}^{2}, \ldots x_{10}, y_{1}, y_{2}, \ldots, y_{10}}" src="https://entrancecorner.oncodecogs.com/gif.latex?%5Cmathrm%7Bx_%7B1%7D%2
The number of ways in which 20 letters be arranged in a line so that suffixes of the letters and also those of are respectively in ascending order of magnitude is