Question: Which Russian mathmatician contributed to number theory, Grigori Perelman or Ivan Fesenko?

Context articles: Soul theorem
Algorithmic Number Theory Symposium
West Coast Number Theory
Disquisitiones Arithmeticae
Grigori Perelman
Fesenko group
Manifold Destiny
Ivan Fesenko
Additive number theory
Arithmetic

In mathematics, the soul theorem is a theorem of Riemannian geometry that largely reduces the study of complete manifolds of non-negative sectional curvature to that of the compact case.
 Cheeger and Gromoll proved the theorem in 1972 by generalizing a 1969 result of Gromoll and Wolfgang Meyer.
 The related soul conjecture was formulated by Gromoll and Cheeger in 1972 and proved by Grigori Perelman in 1994 with an astonishingly concise proof.
Algorithmic Number Theory Symposium (ANTS) is a biennial academic conference, first held in Cornell in 1994, constituting an international forum for the presentation of new research in computational number theory.
 They are devoted to algorithmic aspects of number theory, including elementary number theory, algebraic number theory, analytic number theory, geometry of numbers, algebraic geometry, finite fields, and cryptography.
West Coast Number Theory (WCNT), a meeting that has also been known variously as the Western Number Theory Conference and the Asilomar Number Theory meeting, is an annual gathering of number theorists first organized by D. H. and Emma Lehmer at the Asilomar Conference Grounds in 1969.
 In his tribute to D. H. Lehmer, John Brillhart stated that "There is little doubt that one of [Dick and Emma's] most enduring contributions to the world of mathematicians is their founding of the West Coast Number Theory Meeting [an annual event] in 1969".
 To date, the conference remains an active meeting of young and experienced number theorists alike.
The Disquisitiones Arithmeticae (Latin for "Arithmetical Investigations") is a textbook of number theory written in Latin by Carl Friedrich Gauss in 1798 when Gauss was 21 and first published in 1801 when he was 24.
 It is notable for having a revolutionary impact on the field of number theory as it not only turned the field truly rigorous and systematic but also paved the path for modern number theory.
 In this book, Gauss brought together and reconciled results in number theory obtained by mathematicians such as Fermat, Euler, Lagrange and Legendre and added many profound and original results of his own.
Grigori Yakovlevich Perelman (Russian: Григо́рий Я́ковлевич Перельма́н ; ] ; born 13 June 1966) is a Russian mathematician.
 He made a contribution to Riemannian geometry and geometric topology.
In mathematics, Fesenko groups are certain subgroups of the wild automorphism groups of local fields of positive characteristic (i.e. the Nottingham group), studied by Ivan Fesenko ().
"Manifold Destiny" is an article in "The New Yorker" written by Sylvia Nasar and David Gruber and published in the August 28, 2006 issue of the magazine.
 It claims to give a detailed account (including interviews with many mathematicians) of some of the circumstances surrounding the proof of the Poincaré conjecture, one of the most important accomplishments of 20th and 21st century mathematics, and traces the attempts by three teams of mathematicians to verify the proof given by Grigori Perelman.
Ivan Fesenko (Russian: Иван Борисович Фесенко ; born 1962) is a mathematician working in number theory and other areas of modern mathematics.
In number theory, the specialty additive number theory studies subsets of integers and their behavior under addition.
 More abstractly, the field of "additive number theory" includes the study of abelian groups and commutative semigroups with an operation of addition.
 Additive number theory has close ties to combinatorial number theory and the geometry of numbers.
 Two principal objects of study are the sumset of two subsets "A" and "B" of elements from an abelian group "G",
Arithmetic (from the Greek ἀριθμός "arithmos", "number") is a branch of mathematics that consists of the study of numbers, especially the properties of the traditional operations between them—addition, subtraction, multiplication and division.
 Arithmetic is an elementary part of number theory, and number theory is considered to be one of the top-level divisions of modern mathematics, along with algebra, geometry, and analysis.
 The terms "arithmetic" and "higher arithmetic" were used until the beginning of the 20th century as synonyms for "number theory" and are sometimes still used to refer to a wider part of number theory.