import math
 
INPUT_FILENAME = "move.in"
OUTPUT_FILENAME = "move.out"
 
def isPrime(n):
    if n <= 1:
        return False
    else:
        limit = int(math.sqrt(n))
        for x in xrange(2, limit + 1):
            if n % x == 0:
                return False
 
        return True
 
def nextMove(n):
    if n < 0:
        return abs(n)
    elif isPrime(n):
        return n - 1
    else:
        return n + 3
 
def fromString(string, *types):
    result = []
    for token, desired in zip(string.split(), types):
        result.append(desired(token))
 
    if len(result) is not len(types):
        raise TypeError, "Expected %s" % (types,)
    else:
        return result
 
def readSpec(filename=INPUT_FILENAME):
    inf = open(filename, 'r')
    return fromString(inf.readline(), int, int)
 
def writeResult(result, filename=OUTPUT_FILENAME):
    outf = open(filename, 'w')
    outf.write("%d\n" % result)
 
def doSequence(start, length):
    current = start
    for x in xrange(length - 1):
        current = nextMove(current)
 
    return current
 
def main():
    try:
        writeResult(doSequence(*readSpec()))
    except Exception, e:
        print e
 
if __name__ == "__main__":
    main()

#include <stdio.h>
#include <math.h>
 
int isprime(int i) {
    int k, lim;
 
    if(i<2)    return 0; // Less than 2 is composite
    if(i==2)   return 1; // 2 is prime
    if(i%2==0) return 0; // Divisible by 2 is composite
 
    lim = sqrt(i)+1;
    for(k=3; k<=lim; k+=2) // The standard primality test
        if(i%k==0) return 0;
 
    return 1;
}
 
int main() {
    int n, k;
 
    freopen("move.in", "rt", stdin);
    freopen("move.out", "wt", stdout);
    scanf("%d %d", &n, &k);
 
    while(--k) {
        if(isprime(n)) n -= 1; // Rule #3
        else if(n<0)   n =- n; // Rule #1
        else if(n>0)   n += 3; // Rule #2
    }
 
    printf("%d\n", n);
    return 0;
}

class SMAC:
    def isPrime (self, n):
        if n < 2:
            return False
        elif n == 2:
            return True
        elif n % 2 == 0:
            return False
        else:
            i = 3
            while i * i <= n:
                if n % i == 0:
                    return False
                i += 2
 
            return True
 
    def junior (self):
        args = self.loadFile("reach.in").split()
        if len(args) != 2:
            raise EnvironmentError(1, "Invalid file contents.")
 
        n = int(args[0])
        k = int(args[1])
 
        r = max(self.juniorResults(n, k, 1))
        self.saveFile("reach.out", r)
 
    def juniorResults (self, n, k, i):
        if i > k:
            return [n]
 
        r = []
        r += self.juniorResults(n + i, k, i + 1)
        r += self.juniorResults(n - i, k, i + 1)
        if self.isPrime(n):
            r += self.juniorResults(n * 2, k, i + 1)
        return r
 
if __name__ == '__main__':
    smac = SMAC()
    smac.junior()

#include <stdio.h>
#include <math.h>
 
int max(int a, int b) {
    return a > b ? a : b;
}
 
int isprime(int i) {
    int k, lim;
 
    if(i<2)    return 0; // Less than 2 is composite
    if(i==2)   return 1; // 2 is prime
    if(i%2==0) return 0; // Divisible by 2 is composite
 
    lim = sqrt(i)+1;
    for(k=3; k<=lim; k+=2) // The standard primality test
        if(i%k==0) return 0;
 
    return 1;
}
 
int reach(int n, int i, int k) {
    int r;
    if(i>k) return n;
 
    r = max(reach(n+i, i+1, k),   // Option #1
            reach(n-i, i+1, k));  // Option #2
    if(isprime(n))                // Option #3
        r = max(reach(n*2, i+1, k),  r);
 
    return r; // Return the maximum possible value from all 3 options
}
 
int main() {
    int n, k;
 
    freopen("reach.in", "rt", stdin);
    freopen("reach.out", "wt", stdout);
    scanf("%d %d", &n, &k);
 
    printf("%d\n", reach(n,1,k));
    return 0;
}