#include <bits/stdc++.h>
using namespace std;

inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}

typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<long long> VL;
typedef vector<vector<long long>> VVL;
typedef vector<string> VS;
typedef pair<int, int> P;
typedef tuple<int,int,int> tpl;

#define ALL(a)  (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define REVERSE(c) reverse((c).begin(),(c).end())
#define LB(a,x) lower_bound((a).begin(), (a).end(), x) - (a).begin()
#define UB(a,x) upper_bound((a).begin(), (a).end(), x) - (a).begin()

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define RFOR(i,a,b) for(int i=(a)-1;i>=(b);--i)
#define RREP(i,n) RFOR(i,n,0)

#define en "\n"

constexpr double EPS = 1e-9;
constexpr double PI  = 3.1415926535897932;
constexpr int INF = 2147483647;
constexpr long long LINF = 1LL<<60;
constexpr long long MOD = 1000000007; // 998244353;

#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

void Main(){
    int N,K; cin >> N >> K;
    int ans;
    if(N == 1){
        ans = 1;
    }
    else if(N%2 == 0){
        if(K%2 == 0) ans = min(N/2, K/2+1 + K/2);
        else ans = min(N/2, (K+1)/2 * 2);
    }
    else{
        if(K%2 == 0) ans = min((N+1)/2, K/2+1) + min(N/2, K/2);
        else ans = min(N/2, (K+1)/2) + min((N+1)/2, K/2+1);
    }
    cout << ans << en;
    return;
}

int main(void){
    cin.tie(0);ios_base::sync_with_stdio(0);cout<<fixed<<setprecision(15);
    int t = 1; //cin >> t;
    REP(_,t){
        Main();
    }
    return 0;
}