#pragma GCC optimize ("O3")
#include "bits/stdc++.h"

using namespace std;
using ll = long long int;

#define debugos cout
#define debug(v) {printf("L%d %s > ",__LINE__,#v);debugos<<(v)<<endl;}
#define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:(v)){debugos<<e<<" ";}debugos<<endl;}
#define debuga(m,w) {printf("L%d %s > ",__LINE__,#m);for(int x=0;x<(w);x++){debugos<<(m)[x]<<" ";}debugos<<endl;}
#define debugaa(m,h,w) {printf("L%d %s >\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){debugos<<(m)[y][x]<<" ";}debugos<<endl;}}
#define all(v) (v).begin(),(v).end()
#define repeat(cnt,l) for(auto cnt=remove_reference<decltype(l)>::type();(cnt)<(l);++(cnt))
#define rrepeat(cnt,l) for(auto cnt=(l)-1;0<=(cnt);--(cnt))
#define iterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);++(cnt))
#define diterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);--(cnt))
const ll MD = 1000000007ll; const long double PI = 3.1415926535897932384626433832795L;
inline void assert_call(bool assertion, function<void()> f) { if (!assertion) { cerr << "assertion fault:" << endl; f(); abort(); } }
template<typename T1, typename T2> inline ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << '(' << p.first << ':' << p.second << ')'; return o; }
template<typename Vec> inline ostream& _ostream_vecprint(ostream& os, const Vec& a) {
    os << '['; for (const auto& e : a) os << ' ' << e << ' '; os << ']'; return os; }
template<typename T> inline ostream& operator<<(ostream& o, const vector<T>& v) { return _ostream_vecprint(o, v); }
template<typename T, size_t S> inline ostream& operator<<(ostream& o, const array<T, S>& v) { return _ostream_vecprint(o, v); }
template<typename T> inline T& chmax(T& to, const T& val) { return to = max(to, val); }
template<typename T> inline T& chmin(T& to, const T& val) { return to = min(to, val); }
void bye(string s, int code = 0) { cout << s << endl; exit(code); }
mt19937_64 randdev(8901016);
template<typename T, typename Random = decltype(randdev), typename enable_if<is_integral<T>::value>::type* = nullptr>
inline T rand(T l, T h, Random& rand = randdev) { return uniform_int_distribution<T>(l, h)(rand); }
template<typename T, typename Random = decltype(randdev), typename enable_if<is_floating_point<T>::value>::type* = nullptr>
inline T rand(T l, T h, Random& rand = randdev) { return uniform_real_distribution<T>(l, h)(rand); }

#if defined(_WIN32) || defined(_WIN64)
#define getc_x _getc_nolock
#define putc_x _putc_nolock
#elif defined(__GNUC__)
#define getc_x getc_unlocked
#define putc_x putc_unlocked
#else
#define getc_x getc
#define putc_x putc
#endif
#define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E)
class MaiScanner {
    FILE* fp_;
public:
    inline MaiScanner(FILE* fp):fp_(fp){}
    template<typename T> void input_integer(T& var) noexcept {
        var = 0; T sign = 1;
        int cc = getc_x(fp_);
        for (; cc < '0' || '9' < cc; cc = getc_x(fp_))
            if (cc == '-') sign = -1;
        for (; '0' <= cc && cc <= '9'; cc = getc_x(fp_))
            var = (var << 3) + (var << 1) + cc - '0';
        var = var * sign;
    }
    inline int c() noexcept { return getc_x(fp_); }
    inline MaiScanner& operator>>(int& var) noexcept { input_integer<int>(var); return *this; }
    inline MaiScanner& operator>>(long long& var) noexcept { input_integer<long long>(var); return *this; }
    inline MaiScanner& operator>>(string& var) {
        int cc = getc_x(fp_);
        for (; !isvisiblechar(cc); cc = getc_x(fp_));
        for (; isvisiblechar(cc); cc = getc_x(fp_))
            var.push_back(cc);
        return *this;
    }
    template<typename IT> inline void in(IT begin, IT end) { for (auto it = begin; it != end; ++it) *this >> *it; }
};
class MaiPrinter {
    FILE* fp_;
public:
    inline MaiPrinter(FILE* fp):fp_(fp){}
    template<typename T>
    void output_integer(T var) noexcept {
        if (var == 0) { putc_x('0', fp_); return; }
        if (var < 0)
            putc_x('-', fp_),
            var = -var;
        char stack[32]; int stack_p = 0;
        while (var)
            stack[stack_p++] = '0' + (var % 10),
            var /= 10;
        while (stack_p)
            putc_x(stack[--stack_p], fp_);
    }
    inline MaiPrinter& operator<<(char c) noexcept { putc_x(c, fp_); return *this; }
    inline MaiPrinter& operator<<(int var) noexcept { output_integer<int>(var); return *this; }
    inline MaiPrinter& operator<<(long long var) noexcept { output_integer<long long>(var); return *this; }
    inline MaiPrinter& operator<<(char* str_p) noexcept { while (*str_p) putc_x(*(str_p++), fp_); return *this; }
    inline MaiPrinter& operator<<(const string& str) {
        const char* p = str.c_str();
        const char* l = p + str.size();
        while (p < l) putc_x(*p++, fp_);
        return *this;
    }
    template<typename IT> void join(IT begin, IT end, char sep = ' ') { for (bool b = 0; begin != end; ++begin, b = 1) b ? *this << sep << *begin : *this << *begin; }
};
MaiScanner scanner(stdin);
MaiPrinter printer(stdout);

template <typename T>
class SparseTable {
public:
    int size;
    vector<int> log2;
    vector<T> data;
    vector<T> dp;

    SparseTable(int size) :size(size), log2(size + 1), data(size) {
        // for fast calculate log2
        for (int i = 2; i <= size; ++i) {
            log2[i] = log2[i >> 1] + 1;
        }

        dp.resize(size*(log2[size] + 1));
    }

    inline T& operator[](size_t i) { return data[i]; }
    inline T operator[](size_t i)const { return data[i]; }

    void build() {
        int l, i, f, b;
        for (i = 0; i < size; i++) {
            dp[i] = i;
        }
        for (l = 1; (1 << l) <= size; l++) {
            for (i = 0; i + (1 << l) <= size; i++) {
                f = dp[i + size * (l - 1)];
                b = dp[(i + (1 << (l - 1))) + size * (l - 1)];

                dp[i + size * l] = (data[f] <= data[b]) ? f : b; // minimum
            }
        }
    }

    // range [l,r)
    int getminrangeIdx(int l, int r) const {
        int lg = log2[r - l];
        int i1 = dp[l + size * lg];
        int i2 = dp[r - (1 << lg) + size * lg];
        return (data[i1] <= data[i2]) ? i1 : i2; // minimum
    }
};

//

int N, K;
pair<ll, ll> XA[100010];

//


int main() {
    
    scanner >> N >> K; --K;
    
    repeat(i, N) {
        ll x;
        scanner >> x;
        XA[i].first = x;
    }
    repeat(i, N) {
        ll a;
        scanner >> a;
        XA[i].second = a;
    }
    
    SparseTable<ll> lows(N);
    SparseTable<ll> highs(N);
    
    repeat(i, N) {
        lows[i]  = XA[i].first - XA[i].second;
        highs[i] = -(XA[i].first + XA[i].second);
    }
    lows.build();
    highs.build();
    
    int li = K;
    int ri = K+1;
    repeat(i, N) {
        int l = lows.getminrangeIdx(li, ri);
        int r = highs.getminrangeIdx(li, ri);
        ll left = XA[l].first - XA[l].second;
        ll right = XA[r].first + XA[r].second;
        int nli = distance(XA, lower_bound(XA, XA+N, pair<ll,ll>(left, -2e18))); 
        int nri = distance(XA, upper_bound(XA, XA+N, pair<ll,ll>(right, 2e18))); 
        li = nli;
        ri = nri;
    }
    
    printer << (ri-li) << '\n';
    
    return 0;
}