#include //ios::sync_with_stdio(false); //cin.tie(0); using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair pii; typedef pair ppii; typedef pair pipi; typedef pair pll; typedef pair ppll; typedef pair plpl; typedef tuple tl; ll mod=1000000007; ll mod2=998244353; ll inf=1000000000000000000; double pi=2*acos(0); #define rep(i,m,n) for(ll i=m;i=m;i--) int dh[4]={1,-1,0,0}; int dw[4]={0,0,1,-1}; int ddh[8]={-1,-1,-1,0,0,1,1,1}; int ddw[8]={-1,0,1,-1,1,-1,0,1}; ll lmax(ll a,ll b){ if(a0){ if(k&1)ret*=now; now*=now; k/=2; } return ret; } ll gya[200010]; ll kai[200010]; ll m; ll beki(ll n,ll k){ ll ret=1; ll now=n; while(k>0){ if(k%2==1){ ret*=now; ret%=m; } now*=now; now%=m; k/=2; } return ret; } ll gyaku(ll n){ return beki(n,mod-2); } void nckinit(ll n){ kai[0]=1; kai[1]=1; for(int i=2;i<=n;i++){ kai[i]=kai[i-1]*i; kai[i]%=mod; } gya[n]=gyaku(kai[n]); for(int i=n-1;i>=1;i--){ gya[i]=gya[i+1]*(i+1); gya[i]%=mod; } gya[0]=1; } ll nck(ll n,ll k){ if(k<0)return 0; if(k==0||n==k)return 1; ll ret=kai[n]; ret*=gya[n-k]; ret%=mod; ret*=gya[k]; ret%=mod; return ret; } ll npk(ll n,ll k){ if(k<0)return 0; if(k==0)return 1; ll ret=kai[n]; ret*=gya[n-k]; ret%=mod; return ret; } int main(){ ll n,k;cin>>n>>k; ll x[n],a[n]; rep(i,0,n)cin>>x[i]; rep(i,0,n)cin>>a[i]; ll ma=x[k-1]+a[k-1]; ll mi=x[k-1]-a[k-1]; bool used[n];fill(used,used+n,false); ll mak=0; ll mik=inf; ll r=k-1,l=k-1; used[k-1]=true; rep(i,k,n){ if(x[i]<=ma){ used[i]=true; r++; mak=max(mak,x[i]+a[i]); mik=min(mik,x[i]-a[i]); } else{ r++; break; } } rrep(i,k-2,0){ if(x[i]>=mi){ used[i]=true; l--; mak=max(mak,x[i]+a[i]); mik=min(mik,x[i]-a[i]); } else{ l--; break; } } ma=mak;mi=mik; for(;;){ ll h=mak; ll g=mik; rep(i,r,n){ if(x[i]<=ma){ used[i]=true; mak=max(mak,x[i]+a[i]); mik=min(mik,x[i]-a[i]); } else{ r=i; break; } } rep(i,l,0){ if(x[i]>=mi){ used[i]=true; mak=max(mak,x[i]+a[i]); mik=min(mik,x[i]-a[i]); } else{ l=i; break; } } if(mak==h&&mik==g)break; } ll ans=0; rep(i,0,n)if(used[i])ans++; cout<