Cauchy-Schwarz is pretty helpful

Algebra Level 2

Let \(a\), \(b\), \(c\) and \(d\) be positive reals such that \(a + b + c + d = 1\). Find the minimum value of \(\frac {1}{a} + \frac {1}{b} + \frac {1}{c} + \frac {1}{d}\).