In a particular system of units , a physical quantity can be expressed in terms of the electic charge e , electron mass `m_(e )` , Planck's constant h , and Coulomb's constant `k = 1/(4piepsilon)` , where ` epsilon_(0)` is the permittivity of vacumm . In terms of these physical constants , the dimension of the magnetic field is `[B] = [e]^(alpha)[m_(e )]^(beta) [h]^(gamma)[k]^(delta)` . The value of `alpha + beta + gamma +delta ` is _________.