Definition: In this task, you're given two sentences. Indicate if the first sentence clearly entails the second sentence (i.e., one can conclude the 2nd sentence by reading the 1st one). Indicate your answer with '1' if the first sentence entails the second sentence, otherwise answer with '0'.
Input: Sentence 1: It is unlikely either vessel was operating its active sonar at the time of the collision, because the submarines are designed to "hide" while on patrol and the use of active sonar would immediately reveal the boat's location.  Both submarines' hulls are covered with anechoic tile to reduce detection by sonar, so the boats' navigational passive sonar would not have detected the presence of the other. Sentence 2: Two submarines have collided.

1