In the context of integrability in AdS/CFT correspondence, we construct the Green-Schwarz-Metsaev-Tseytlin supersting in the S(5) x R(1) sector, from a set of physical particles on a circle in the integrable 1+1D sigma-model with Zamolodchikov's S-matrix. We reproduce, in the limit of high density of the particles, all finite gap KMMZ solutions for classical strings and the quantum AFS string Bethe ansatz equations, as an approximation to our construction.