S1: Mount Everest is the tallest peak in the world. S2: K2 in the Karakoram Range is taller than Mount Everest. The second sentence:

The first sentence asserts that Mount Everest is the tallest peak. The second sentence directly opposes this by claiming K2 is taller than Mount Everest. Both statements cannot be true at the same time - they make mutually exclusive claims about which peak is tallest. This is direct contradiction. Therefore, the second sentence contradicts the assertion of the first.