Two goods are substitutes when an increase in the price of one increases demand for the other -- for example, Coca-Cola and Pepsi . Two goods are complements when an increase in the price of one decreases demand for the other -- for example, skis and other skiing equipment (poles, boots, and so on).
Higher input prices make it more expensive
to produce a good, which reduces supply. (In other words, sellers
would need to receive a higher price to be willing to sell the same amount.)
For example, an increase in the price of paper raises the prices
of newspapers, magazines, and books.