import std.stdio, std.conv, std.functional, std.string; import std.algorithm, std.array, std.container, std.range, std.typecons; import std.numeric, std.math, std.random; import core.bitop; string FMT_F = "%.10f"; static string[] s_rd; T RD(T = long)() { while(!s_rd.length) s_rd = readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; } string RDR()() { return readln.chomp; } T[] ARR(T = long)(in string str, T fix = 0) { auto r = str.split.to!(T[]); r[] += fix; return r; } T[] RDA(T = long)(T fix = 0) { auto r = readln.chomp.split.to!(T[]); r[] += fix; return r; } T[][] RDA2(T = long)(size_t n, T[] fix = []) { auto r = new T[][](n); foreach (i; 0..n) { r[i] = readln.chomp.split.to!(T[]); foreach (j, e; fix) r[i][j] += e; } return r; } size_t[] MAKE_IDX(alias less = "a < b", Range)(Range range) { auto idx = new size_t[](range.length); makeIndex!(less)(range, idx); return idx;} size_t MIN_POS(alias less = "a < b", Range)(Range range) { auto r = minPos!(less)(range); return range.length - r.length; } bool inside(T)(T x, T b, T e) { return x >= b && x < e; } long lcm(long x, long y) { return x * y / gcd(x, y); } long mod = 10^^9 + 7; //long mod = 998244353; //long mod = 1_000_003; void moda(ref long x, long y) { x = (x + y) % mod; } void mods(ref long x, long y) { x = ((x + mod) - (y % mod)) % mod; } void modm(ref long x, long y) { x = (x * y) % mod; } void main() { auto N = RD; auto K = RD-1; auto X = RDA; auto A = RDA; long ans = 1; long last; foreach (i; K..N-1) { auto d = X[i+1] - X[i]; auto r = max(last, A[i]); last = r - d; if (d <= r) ++ans; else break; } last = 0; foreach_reverse (i; 1..K+1) { auto d = X[i] - X[i-1]; auto r = max(last, A[i]); last = r - d; if (d <= r) ++ans; else break; } writeln(ans); stdout.flush(); debug readln(); }