#include #define rep(i, n) for (int i = 0; i < int(n); i++) #define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--) #define reps(i, n) for (int i = 1; i <= int(n); i++) #define rreps(i, n) for (int i = int(n); i >= 1; i--) #define repc(i, n) for (int i = 0; i <= int(n); i++) #define rrepc(i, n) for (int i = int(n); i >= 0; i--) #define repi(i, a, b) for (int i = int(a); i < int(b); i++) #define repic(i, a, b) for (int i = int(a); i <= int(b); i++) #define all(a) (a).begin(), (a).end() #define bit32(x) (1 << (x)) #define bit64(x) (1ll << (x)) #define sz(v) ((int) v.size()) using namespace std; using i64 = long long; using f80 = long double; using vi32 = vector; using vi64 = vector; using vf80 = vector; using vstr = vector; void yes() { cout << "Yes" << endl; exit(0); } void no() { cout << "No" << endl; exit(0); } template class pqasc : public priority_queue, greater> {}; template class pqdesc : public priority_queue, less> {}; template void amax(T &x, T y) { x = max(x, y); } template void amin(T &x, T y) { x = min(x, y); } template T exp(T x, i64 n, T e = 1) { T r = e; while (n > 0) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; } template istream& operator>>(istream &is, vector &v) { for (auto &x : v) is >> x; return is; } template ostream& operator<<(ostream &os, vector &v) { rep(i, v.size()) { if (i) os << ' '; os << v[i]; } return os; } void solve(); int main() { ios::sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(16); solve(); return 0; } const int INF = 1001001001; const int dx[] = {1, 0, -1, 0}; const int dy[] = {0, 1, 0, -1}; void solve() { int n, k; cin >> n >> k; k -= 1; vi64 x(n), a(n); cin >> x >> a; int ans = 1; { i64 mi = x[k] - a[k]; for (int i = k - 1; i >= 0; i--) { if (mi <= x[i]) { ans += 1; amin(mi, x[i] - a[i]); } else { break; } } } { i64 ma = x[k] + a[k]; for (int i = k + 1; i < n; i++) { if (ma >= x[i]) { ans += 1; amax(ma, x[i] + a[i]); } else { break; } } } cout << ans << endl; }