#include <bits/stdc++.h>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define vec_input(v) for(auto it=v.begin();it!=v.end();it++){cin>>*it;}
#define vec_output(v) for(auto it=v.begin();it!=v.end();it++){if(it!=v.begin())cout<<" ";cout<<*it;}cout<<endl;
#define vec_debug(v) for(auto it=v.begin();it!=v.end();it++){cerr<<*it<<" ";}cerr<<endl;
#define yn(ans) cout<<(ans?"Yes":"No")<<endl
#define YN(ans) cout<<(ans?"YES":"NO")<<endl
using namespace std;
using ll = long long;
template <typename T>T digitsum(T n);
template <typename T>bool isPrime(T n);
template <typename T>vector<pair<T, T>> prime_factor(T n);
long long int intpow(long long int,long long int);
template <typename T>T intlog(T);
long long int combination(long long int,long long int);
long long int series_sum(long long int);

int main(){
    int n,k;
    cin>>n>>k;
    cout<<((n>=k)?intpow(2,n-k):0)<<endl;
}

/*int main(){
    int n,maxv=0,maxv2=0;
    cin>>n;
    vector<int> vec(n),vec2(n);
    rep(i,n){
        cin>>vec[i];
        maxv=max(maxv,vec[i]);
    }
    ll ans=0;
    rep(i,n){
        vec2[i]=maxv-vec[i];
        if(vec2[i]>maxv2){
            maxv2=vec2[i];
        }
    }
    while(maxv2>=1){
        ans++;
        
    }
}*/

/*int main(){
    int x,i;
    cin>>x;
    if(360%x==0)cout<<360/x<<endl;
    else {
        for(i=0;(360*i)%x!=0;i++){
            break;
        }
        cout<<360*i/x<<endl;
    }
}*/

/*int main(){
    int n,m,a,b;
    cin>>n>>m;
    a=n/m;
    b=n-a*m;
    rep(i,m-b){
        cout<<a<<" ";
    }
    rep(i,b){
        cout<<a+1<<" ";
    }
    cout<<endl;
}*/

/*int main(){
    vector<int> vec(4);
    vec_input(vec);
    sort(all(vec));
    cout<<abs(vec[3]+vec[0]-vec[1]-vec[2])<<endl;
}*/

/*int main(){
    int t,a,b,c,maxv,minv,mid;
    cin>>t;
    rep(l,t){
        cin>>a>>b>>c;
        maxv=max(a,max(b,c));
        minv=min(a,min(b,c));
        mid=a+b+c-minv-maxv;
        YN(maxv*maxv==minv*minv+mid*mid);
    }
}*/

/*int main(){
    int a,b;
    while(scanf("%d %d",&a,&b)!=EOF){
        cout<<intlog(a+b)+1<<endl;
    }
}*/

/*int main(){
    vector<int> vec(10);
    vec_input(vec);
    sort(rall(vec));
    rep(i,3){
        cout<<vec[i]<<endl;
    }
}*/

/*int main(){
    for(int i=1;i<=9;i++){
        for(int j=1;j<=9;j++){
            cout<<i<<"x"<<j<<"="<<i*j<<endl;
        }
    }
}*/

/*int main(){
    int n,mid1,mid2;
    cin>>n;
    vector<int> vec(n),vec2(n);
    rep(i,n){
        cin>>vec[i];
        vec2[i]=vec[i];
    }
    sort(rall(vec2));
    mid1=vec2[n/2-1];
    mid2=vec2[n/2];
    rep(i,n){
        if(vec[i]<=mid2)cout<<mid1<<endl;
        else cout<<mid2<<endl;
    }
}*/

/*int main(){
    int n,ans=0,t;
    cin>>t;
    rep(l,t){
        cin>>n;
        ans=0;
        if(n%2==0)ans++;
        cout<<combination(n,n-1)/2-ans<<endl;
    }
}*/

/*int main(){
    int n;
    cin>>n;
    cout<<n*10<<endl;
}*/

/*int main(){
    int n,m,d;
    cin>>n;
    unordered_map<int,int> map1;
    rep(i,n){
        cin>>d;
        if(map1.count(d)){
            map1[d]++;
        }else{
            map1[d]=1;
        }
    }
    cin>>m;
    unordered_set<int> set;
    unordered_map<int,int> map2;
    rep(i,m){
        cin>>d;
        if(map2.count(d)){
            map2[d]++;
        }else{
            set.insert(d);
            map2[d]=1;
        }
    }
    int ans=1;
    for (auto value : set) {
        if(map1[value]<map2[value]){
            ans=0;
            break;
        }
    }
    YN(ans);
}*/

/*int main(){
    ll t,a,b,c,d;
    cin>>t;
    rep(l,t){
        cin>>a>>b>>c>>d;
        cout<<b<<" "<<c<<" "<<c<<endl;
    }
}*/

/*int main(){
    ll n;
    cin>>n;
    cout<<(ll)(n*1.5)<<endl;
}*/

/*int main(){
    ll n,x,ans;
    cin>>n>>x;
    vector<int> vec(n);
    rep(i,n){
        cin>>vec[i];
        if(i==0) ans=abs(vec[i]-x);
        else ans=__gcd(ans,abs(vec[i]-x));
    }
    cout<<ans<<endl;
}*/

/*int main(){
    int n,k;
    cin>>n>>k;
    vector<int> vec(n);
    vec_input(vec);
    sort(all(vec));
    double ans=0;
    for(int i=n-k;i<n;i++){
        ans=(ans+(double)vec[i])/2;
    }
    printf("%.8lf\n",ans);
}*/

/*int main(){
    int ans=31;
    string s,t;
    cin>>s>>t;
    if(s=="Sat"||s=="Sun"){ans++;
    if(t=="Sat"||t=="Sun")ans++;
    }
    cout<<"8/"<<ans<<endl;
}*/

/*int main(){
    int t,n,a,b;
    cin>>t;
    rep(l,t){
        cin>>n;
        YN(n%4==0);
        if(n%4==0){
            a=0,b=0;
            rep(i,n/2){
                cout<<2*(i+1)<<" ";
                a+=2*(i+1);
            }
            rep(i,n/2-1){
                cout<<2*(i+1)-1<<" ";
                b+=2*(i+1)-1;
            }
            cout<<a-b<<endl;
        }
    }
}*/

/*int main(){
    ll a=0,b=0;
    string s;
    cin>>s;
    reverse(all(s));
    rep(i,s.length()){
        if(i%2==0)a+=stoi(s.substr(i,1));
        else b+=stoi(s.substr(i,1));
    }
    cout<<b<<" "<<a<<endl;
}*/

/*int main(){
    ll t,n,d,a,b;
    cin>>t;
    rep(l,t){
        cin>>n;
        a=0,b=0;
        a+=pow(2,n);
        for(int i=1;i<n;i++){
            if(i<n/2)a+=pow(2,i);
            if(i>=n/2)b+=pow(2,i);
        }
        cout<<abs(a-b)<<endl;
    }
}*/

/*int main(){
    int t;
    cin>>t;
    ll a,b;
    rep(l,t){
        cin>>a>>b;
        cout<<a+b<<endl;
    }
}*/

/*int main(){
    int a,b,ans;
    cin>>a>>b;
    if(a>b)ans=0;
    else if(a==b)ans=4;
    else if(a*a>b*b/4)ans=8;
    else if(a*a==b*b/4)ans=4;
    else ans=0;
    cout<<ans<<endl;
}*/

/*int main(){
    string str;
    getline(cin,str);
    rep(i,str.length()){
        if(str[i]==' '){
            cout<<",";
            for(i;str[i]==' ';i++){}
            i--;
        }
        else cout<<str[i];
    }
    cout<<endl;
}*/

/*int main(){
    string s;
    cin>>s;
    ll ans=0,d=0,m=0,p=0,l=0,r=0,minv=0;
    rep(i,s.length()){
        if(s[i]=='>'){
            if(d==1){
                l=abs(minv)+(p-m);
                ans+=max(r,l);
                ans+=abs(minv)*(p+m-1);
                d=0;
                m=0;
                p=0;
            }else{
                m++;
                minv=min(minv,-m);
            }
        }else{
            d=1;
            p++;
        }
        cerr<<p-m<<endl;
        ans+=p-m;
    }
    cout<<ans<<endl;
}*/

/*int main(){
    int a,b,ans=0;
    cin>>a>>b;
    if(b==1){
        ans=1;
    }else{
        vector<int> vec;
        for(int i=2;i<=a;i++){
            if(a%i==0)vec.push_back(i);
        }
        rep(i,vec.size()){
            if(vec[i]%b==0){
                ans=1;
                break;
            }
        }
    }
    YN(ans);
}*/

/*int main(){
    ll a,b,i;
    cin>>a>>b;
    for(i=0;a<=b;i++){
        a=3*a;
        b=2*b;
    }
    cout<<i<<endl;
}*/

/*int main(){
    ll n,m,ans=0;
    cin>>n>>m;
    if(m>2*n){
        ans+=n;
        m-=2*n;
        ans+=m/4;
    }else{
        ans+=m/2;
    }
    cout<<ans<<endl;
}*/

/*int main(){
    int maxv=0,a,cur=0,t;
    cin>>t;
    rep(i,t){
        cin>>a;
        cur-=a;
        cerr<<cur<<endl;
        maxv=max(maxv,cur);
        cin>>a;
        cur+=a;
        maxv=max(maxv,cur);
    }
    cout<<maxv<<endl;
}*/

/*int main(){
    ll x,y,n;
    cin>>x>>y>>n;
    if(x<=n&&y<=n)n-=2;
    else if(x<=n)n--;
    else if(y<=n)n--;
    cout<<n<<endl;
}*/

/*int main(){
    string s,t="hello";
    cin>>s;
    int j=0;
    rep(i,s.length()){
        if(s[i]==t[j]){
            j++;
        }
    }
    YN(t.length()==j);
}*/

/*int main(){
    ll n;
    cin>>n;
    vector<ll> vec(n);
    vec_input(vec);
    list<ll> list;
    rep(i,n){
        if(i%2==0){
            list.push_back(vec[i]);
        }else{
            list.push_front(vec[i]);
        }
    }
    if(n%2==1)reverse(all(list));
    vec_output(list);
}*/

/*int main(){
    ll n,p,ans=1,counter=0,j;
    cin>>n>>p;
    vector<pair<ll,ll>> vec=prime_factor(p);
    rep(i,vec.size()){
        if(vec[i].second>=n){
            for(j=1;j*n<=vec[i].second;j++){}
            ans*=pow(vec[i].first,j-1);
        }
    }
    cout<<ans<<endl;
}*/

/*int main(){
    ll k,n,w,ans=0,money=0;
    cin>>k>>n>>w;
    while(ans<w){
        ans++;
        money+=ans*k;
    }
    cout<<(n>money? 0:money-n)<<endl;
}*/

/*int main(){
    struct point{int x,y;};
    vector<point> vec(3);
    vec[0].x=2;
    vec[0].y=8;
    vec[1].x=3;
    vec[1].y=9;
    vec[2].x=7;
    vec[2].y=9;
    point p1,p2;
    ll n;
    cin>>n;
    rep(i,n){
        cin>>p1.x>>p1.y>>p2.x>>p2.y;
        rep(j,3){
            if(p1.x==vec[j].x&&p1.y==vec[j].y){
                vec[j].x=p2.x;
                vec[j].y=p2.y;
            }
        }
    }
    YN(vec[0].x==5&&vec[0].y==8
      &&vec[1].x==4&&vec[1].y==8
      &&vec[2].x==6&&vec[2].y==8);
}*/

/*int main(){
    ll r,g,b,n,ans=0,b2;
    cin>>r>>g>>b>>n;
    for(int i=0;i*r<=n;i++){
        for(int j=0;j*g<=n;j++){
            b2=n-i*r-j*g;
            if(b2<0)break;
            if(b2%b==0){
                //cerr<<i*r<<" "<<j*g<<" "<<b2<<endl;
                ans++;
            }
        }
    }
    cout<<ans<<endl;
}*/

/*int main(){
    int n;
    cin>>n;
    vector<int> vec(n);
    vec_input(vec);
    sort(vec.rbegin(),vec.rend());
    vector<int> time(2,0);
    rep(i,n){
        sort(all(time));
        time[0]+=vec[i];
    }
    sort(all(time));
    cout<<time[1]<<endl;
}*/

/*int main(){
    long long int ans,a,b,c,d;
    cin>>a>>b>>c>>d;
    ans=b-a+1;
    long long int e=0;
    e+=(b/c)-(a/c);
    if(a%c==0)e++;
    e+=(b/d)-(a/d);
    if(a%d==0)e++;
    long long int f=c*d/__gcd(c,d);
    e-=(b/f)-(a/f);
    if(a%(f)==0)e--;
    cout<<ans-e<<endl;
}*/

/*int main(){
    string s;
    cin>>s;
    int ans=1;
    rep(i,s.length()){
        if(s[i]!='4'&&s[i]!='7'){
            ans=0;
            break;
        }
    }
    int n=stoi(s);
    int d=1,a,digit,counter=0;
    for(int i=4;i<=n;i++){
        if(n%i==0){
            d=1;
            digit=intlog(i)+1;
            cerr<<digit<<endl;
            counter=0;
            for(int j=0;j<digit;j++){
                a=(i/d)%10;
                d*=10;
                if(a==4||a==7)counter++;
            }
            if(counter==digit){
                ans=1;
                break;
            }
        }
    }
    YN(ans);
}*/

/*int main(){
    double p;
    cin>>p;
    //0.5=p*n;
    double ans=p/(1-p);
    printf("%.8lf\n",ans);
}*/

/*int main(){
    ll n;
    cin>>n;
    ll maxv=n,i=0;
    while(n!=1){
        i++;
        if(n%2==0)n/=2;
        else n=3*n+1;
        if(n>maxv){
            maxv=n;
        }
    }
    cout<<i<<endl<<maxv<<endl;
}*/

/*int main(){
    struct point{int x,y,z;};
    int n;
    cin>>n;
    point input,sum;
    sum.x=0;
    sum.y=0;
    sum.z=0;
    rep(i,n){
        cin>>input.x>>input.y>>input.z;
        sum.x+=input.x;
        sum.y+=input.y;
        sum.z+=input.z;
    }
    YN(sum.x==0&&sum.y==0&&sum.z==0);
}*/

/*int main(){
    ll n,m,ans;
    cin>>n>>m;
    if(n==1||m==1){
        if(n==1&&m==1)ans=1;
        else if(n==1)ans=m-2;
        else if(m==1)ans=n-2;
    }else if(n==2||m==2){
        ans=0;
    }else{
        ans=(m-2)*(n-2);
    }
    cout<<ans<<endl;
}*/

/*int main(){
    int a,b,odd=0,even=0,ans=0;
    rep(i,3){
        cin>>a>>b;
        if(a%2==1)odd++;
    }
    if(odd%2==0)ans=1;
    cout<<(ans?":-)":":-(")<<endl;
}*/

/*int main(){
    string s;
    cin>>s;
    set<char> set;
    rep(i,s.length()){
        set.insert(s[i]);
    }
    cout<<(set.size()%2==0?"CHAT WITH HER!":"IGNORE HIM!")<<endl;
}*/

/*int main(){
    int n,k;
    cin>>n>>k;
    vector<int> vec(n);
    vector<double> p(n);
    rep(i,n){
        cin>>vec[i];
        p[i]=(double)series_sum(vec[i])/vec[i];
    }
    double ans=0,value=0;
    rep(i,n){
        if(i<=k-1){
            value+=p[i];
            ans=value;
        }else{
            value+=p[i]-p[i-k];
            ans=max(ans,value);
        }
    }
    printf("%.8lf\n",ans);
}*/

/*int main(){
    int n;
    cin>>n;
    printf("%.8lf\n",(double)1/n);
}*/

/*int main(){
    int n;
    cin>>n;
    string s;
    cin>>s;
    ll ans=0;
    rep(i,n-1){
        if(s[i]==s[i+1])ans++;
    }
    cout<<ans<<endl;
}*/

/*int main(){
    unordered_map<ll,ll> map;
    unordered_set<ll> set;
    ll n;
    cin>>n;
    vector<ll> vec(n);
    rep(i,n){
        cin>>vec[i];
        if(set.count(vec[i])){
            map[vec[i]]++;
        }else{
            set.insert(vec[i]);
            map[vec[i]]=1;
        }
    }
    ll ans=0;
    for(auto it=set.begin();it!=set.end();it++){
        ans+=(ll)(map[*it]*(map[*it]-1))/2;
    }
    rep(i,n){
        cout<<ans-map[vec[i]]+1<<endl;
    }
}*/

long long int series_sum(long long int n){
    long long int ans=0;
    for(long long int i=1;i<=n;i++){
        ans+=i;
    }
    return ans;
}

long long int combination(long long int a,long long int b){
    queue<long long int> bunsi,bunbo;
    long long int ans=1;
    b=min(b,a-b);
    for(int i=0;i<b;i++){
        bunsi.push(a-i);
        if(b-i>=2)bunbo.push(b-i);
    }
    while(bunsi.size()!=0||bunbo.size()!=0){
        ans*=bunsi.front();
        bunsi.pop();
        if(ans%bunbo.front()==0){
            ans/=bunbo.front();
            bunbo.pop();
        }
    }
    return ans;
}

/*int main(){
    int a,b,m;
    cin>>a>>b>>m;
    vector<int> fri(a),ran(b);
    con_input(fri);
    con_input(ran);
    int x,y,c,minv;
    rep(i,m){
        cin>>x>>y>>c;
        if(i==0)minv=fri[x-1]+ran[y-1]-c;
        else{
            minv=min(minv,fri[x-1]+ran[y-1]-c);
        }
    }
    sort(all(fri));
    sort(all(ran));
    minv=min(minv,fri[0]+ran[0]);
    cout<<minv<<endl;
}*/

/*int main(){
    ll h;
    cin>>h;
    ll ans=0,d=1;
    while(h>=1){
        h/=2;
        ans+=d;
        d*=2;
    }
    cout<<ans<<endl;
}*/

/*int main(){
    int h,w,n;
    cin>>h>>w>>n;
    cout<<(int)floor((n+max(h,w)-1)/max(h,w))<<endl;
}*/

/*int main(){
    int a,b;
    cin>>a>>b;
    cout<<(a*b==15?"*":a+b==15?"+":"x")<<endl;
}*/

/*int main(){
    int n,d=0,x;
    cin>>n;
    vector<pair<string,int>> vec(n);
    string s,t;
    rep(i,n){
        cin>>t>>x;
        vec[i]=make_pair(t,x);
    }
    cin>>s;
    int ans=0;
    rep(i,n){
        if(d==1){
            ans+=vec[i].second;
        }
        if(vec[i].first==s){
            d=1;
        }
    }
    cout<<ans<<endl;
}*/

/*int main(){
    long long int a,b;
    cin>>a>>b;
    cout<<a*b/__gcd(a,b)<<endl;
}*/

/*int main(){
    int x,n,j=0;
    int ans=0;
    cin>>n;
    rep(i,n){
        cin>>x;
        if(x-1!=j){
            ans++;
        }else{
            j++;
        }
    }
    cout<<(ans==n?-1:ans)<<endl;
}*/

/*int main(){
    int m1,d1,m2,d2;
    cin>>m1>>d1>>m2>>d2;
    cout<<(m1!=m2?1:0)<<endl;
}*/

/*int main(){
    string s;
    string str;
    cin>>s;
    int ans=0,j;
    rep(i,s.length()){
        if(i==0){
            str=s.substr(0,1);
            ans++;
        }else{
            j=1;
            if(i==s.length()-1&&s.substr(i,j)==str)break;
            while(s.substr(i,j)==str){
                j++;
            }
            str=s.substr(i,j);
            i+=j-1;
            ans++;
        }
    }
    cout<<ans<<endl;
}*/

/*int main(){
    ll n,a,b,d1,d2;
    cin>>n>>a>>b;
    ll ans;
    if((b-a)%2==0)ans=(b-a)/2;
    else{
        d1=a-1;
        d2=n-b;
        ans=min(d1,d2)+1+(b-a-1)/2;
    }
    cout<<ans<<endl;
}*/

/*int main(){
    int n,ans=1,j;
    cin>>n;
    vector<int> vec(n);
    vector<bool> vec2(n,true);
    con_input(vec);
    rep(i,n-1){
        if(vec[i]-vec[i+1]>=2){
            ans=0;
            break;
        }
        if(vec[i]-vec[i+1]==1){
            vec[i]--;
            vec2[i]=false;
            j=i;
            while(j>=1&&vec[j-1]>vec[j]){
                if(vec2[j-1]){
                    vec[j-1]--;
                    vec2[j-1]=false;
                    j--;
                }else{
                    ans=0;
                    break;
                }
            }
        }
        if(ans==0)break;
    }
    cout<<(ans?"Yes":"No")<<endl;
}*/

/*int main(){
    string s;
    cin>>s;
    char c='2';
    int counter=0,ans=0;
    rep(i,s.length()){
        if(s[i]!=c){
            counter=1;
            c=s[i];
        }else{
            counter++;
            if(counter>=7){
                ans=1;
                break;
            }
        }
    }
    cout<<(ans?"YES":"NO")<<endl;
}*/

/*int main(){
    char s[100];
    int ans=1,a=0;
    fgets(s, 100, stdin);
    for(int i=0;s[i]!='\n';i++){
        if(i%2==0&&!(s[i]>='a'&&s[i]<='z')){
            ans=0;
            break;
        }
        if(i%2==1&&s[i]!=' '){
            ans=0;
            break;
        }
    }
    cout<<(ans?"Yes":"No")<<endl;
}*/

template <typename T>
T digitsum(T n){
    string s=to_string(n);
    T sum=0;
    T d=1;
    for(T e=0;e<s.length();e++){
        sum+=(n/d)%10;d*=10;
    }
    return sum;
}
template <typename T>
bool isPrime(T n){
    if(n<=1)return false;
    if(n==2)return true;
    if(n%2==0)return false;
    for(T q=3;q*q<=n;q+=2){
        if(n%q==0)return false;
    }
    return true;
}
template <typename T>
vector<pair<T, T>> prime_factor(T n) {
    vector<pair<T, T>> ret;
    if(n%2==0){
        T tmp = 0;
        while (n % 2 == 0) {
            tmp++;
            n /= 2;
        }
        ret.push_back(make_pair(2, tmp));
    }
    for (T i = 3; i*i <= n; i+=2) {
        if(n%i==0){
            T tmp = 0;
            while (n % i == 0) {
                tmp++;
                n /= i;
            }
            ret.push_back(make_pair( i, tmp));
        }
    }
    if (n != 1) ret.push_back(make_pair(n, 1));
    return ret;
}
long long int intpow(long long int x,long long int n){
    long long int ans=1;
    for(int i=0;i<n;i++){
        ans*=x;
    }
    return ans;
}
template <typename T>T intlog(T x){
    string a=to_string(x);
    return a.length()-1;
}