Kautilya's Arthashastra 10.5.26

10.5.26

pattibāhulyaṃ pratyāpāvaḥ //

Excess of the army is called surplus (ávápa); deficiency in infantry is called absence of surplus (pratyávápa); excess of any one of the four constituents of the army is akin to surplus (anvávápa); excess of traitors is far from surplus (atyávápa); in accordance with one's own resources, one should increase one's army from four to eight times the excess of the enemy's army or the deficiency in the enemy's infantry.