Decays of the Y(5S) resonance to channels with B^+ and B^0 mesons are studied using a 23.6 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider. Fully reconstructed B^+ -> J/psi K^+, B^0 -> J/psi K^{*0}, B^+ -> bar{D}^0 pi^+ and B^0 -> D^- pi^+ decays are used to obtain the charged and neutral B production rates per bbar{b} event, f(B^+) = (72.1 ^{+3.9}_{-3.8} pm 5.0)% and f(B^0) = (77.0 ^{+5.8}_{-5.6} pm 6.1)%. Assuming equal rates to B^+ and B^0 mesons in all channels produced at the Y(5S) energy, we measure the fractions for transitions to two-body and three-body channels with B meson pairs, f(Bbar{B}) = (5.5 ^{+1.0}_{-0.9} pm 0.4)%, f(Bbar{B}^* + B^*bar{B}) = (13.7 pm 1.3 pm 1.1)%, f(B^*bar{B}^*) = (37.5 ^{+2.1}_{-1.9} pm 3.0)%, f(Bbar{B}pi) = (0.0 pm 1.2 pm 0.3)%, f(Bbar{B}^*pi + B^*bar{B}pi) = (7.3 ^{+2.3}_{-2.1} pm 0.8)%, and f(B^*bar{B}^*pi) = (1.0 ^{+1.4}_{-1.3} pm 0.4)%. The latter three fractions are obtained assuming isospin conservation.
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