import java.util.Map;
import java.util.Scanner;
import java.io.OutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.io.PrintWriter;
import java.util.HashMap;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author aajjbb
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        EasyNumberChallenge solver = new EasyNumberChallenge();
        solver.solve(1, in, out);
        out.close();
    }
}

class EasyNumberChallenge {
    public void solve(int testNumber, Scanner in, PrintWriter out) {
        int a = in.nextInt(), b = in.nextInt(), c = in.nextInt();
        Map<Triplet, Long> map = new HashMap<Triplet, Long>();
        long ans = 0L;
        for(int i = 1; i <= a; i++) {
            for(int j = 1; j <= b; j++) {
                for(int k = 1; k <= c; k++) {
                    Triplet now = new Triplet(i, j, k);
                    if(map.containsKey(now)) {
                        ans += map.get(now);
                    } else {
                        long tmp = countDiv(i*j*k);
                        map.put(now, tmp);
                        ans += tmp;
                    }
                }
            }
        }
        out.println(ans);
    }
    public long countDiv(long n) {
        if(n == 1L) return 1L;

        int x = (int) Math.sqrt(n);
        int counter = 0;

        for(int i = 1; i <= x; i++) {
            if(n % i == 0) {
                counter += 2;
            }
        }
        if(x * x == n) counter -= 1;
        return counter;
    }
    class Triplet {
        public int a, b, c;

        public Triplet(int a1, int b1, int c1) {
            int[] tmp = {a1, b1, c1};
            Arrays.sort(tmp);
            a = tmp[0]; b = tmp[1]; c = tmp[2];
        }

        @Override
        public boolean equals(Object o) {
            Triplet triplet = (Triplet) (o);
            return (this.a == triplet.a) && (this.b == triplet.b) && (c == triplet.c);
        }
    }
}