Sample size from Chebyshev's inequality for a proportion of heads

Let $S_n$ denote the number of heads obtained in $n$ independent tosses of a fair coin. Using Chebyshev's inequality, the smallest values of $n$ such that

$$P\left(\left|\frac{S_n}n-\frac12\right|\le0.1\right)\ge\frac34,$$

is