The file p32.wk1 contains informatio for the period 1991:1-2015:4 of the following variables:
- p1, price index of the economy 1
- p2, price index of the economy 2
- tcn, nominal exchange rate bewteen the currencies of economies 1 and 2.

With this information, you should
- Estimate the best posible model with the previous information
- interpret the model in economic terms
- predict the values for 2016.