Convert from twain to pie [Spanish]

Unit Definition (twain)
The twain is an old word for the number two, derived from the Anglo-Saxon twegen. The American author Samuel Clemens (1835-1910), who had been a riverboat pilot on the Mississippi in his youth, took his literary name from a traditional riverboat phrase "mark twain", meaning "exactly two" fathoms of water. This was the minimum depth needed for the boats to operate safely without running aground.

Unit Definition (pie [Spanish])
The pie is a traditional foot of Spain. The pie equals 1/3 vara or 12 pulgadas. The pie used in Spain is about 27.86 centimeters or 10.97 inches, but in Spanish Latin America the pie is generally longer.