Let M be a compact Riemannian manifold with boundary. We show that M is
Gromov-Hausdorff close to a convex Euclidean region D of the same dimension
if the boundary distance function of M is C1-close to that of D. More
generally, we prove the same result under the assumptions that the boundary
distance function of M is C0-close to that of D, the volumes of M and
D are almost equal, and volumes of metric balls in M have a certain lower
bound in terms of radius.Comment: 16 pages, v3: added a preliminaries sectio