The sequence s_{1}, s_{2}, s_{3}, ...s_{n},... is such that s_{n} = \frac{1}{n} - \frac{1}{n +1} for all integers n\ge 1. If k is a positive integer, is the sum of the first k terms of the sequence greater than \frac{9}{10}?
(1) k > 10
(2) k < 19
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