We introduce a method for extracting the cusp anomalous dimension at L loops from four-gluon amplitudes in N = 4 Yang-Mills without evaluating any integrals that depend on the kinematical invariants. We show that the anomalous dimension only receives contributions from the obstructions introduced in hep-th/0601031. We illustrate this method by extracting the two-and three-loop anomalous dimensions analytically and the four-loop one numerically. The four-loop result was recently guessed to be f (4) = − 4ζ 3 2 + 24ζ 2 ζ 4 + 50ζ 6 − 4(1 + r)ζ 2 3 with r = −2 using integrability and string theory arguments in hep-th/0610251. Simultaneously, f (4) was computed numerically in hep-th/0610248 from the four-loop amplitude obtaining, with best precision at the symmetric point s = t, r = −2.028(36). Our computation is manifestly s/t independent and improves the precision to r = −2.00002(3), providing strong evidence in favor of the conjecture. The improvement is possible due to a large reduction in the number of contributing terms, as well as a reduction in the number of integration variables in each term.