Given a prime p and a real number λ∈(0,1). Let s and t be positive integers such that s⩽t<12λp. S and T are sets of s and t consecutive positive integers respectively, which satisfy ∣{(x,y)∈S×T:kx≡y(modp)}∣⩾1+λs.Prove that there exists integers a and b that 1⩽a⩽λ1, ∣b∣⩽λst and ka≡b(modp). number theorycombinatoricslattice points