#include <bits/stdc++.h>
using namespace std;
int n;
int t[1000000];
int d(int x) {
  if (t[x] != 0) return t[x];
  int s = 0;
  while ((s + 1) * (s + 1) <= x) s++;
  int w = 0;
  for (int i = 1; i <= s; i++)
    if (x % i == 0) w += 2;
  if (s * s == x) w--;
  t[x] = w;
  return t[x];
}
int main() {
  int a, b, c;
  int M = 1 << 30;
  int w = 0;
  scanf("%d %d %d", &a, &b, &c);
  for (int i = 1; i <= a; i++)
    for (int j = 1; j <= b; j++)
      for (int k = 1; k <= c; k++) {
        w = (w + d(i * j * k)) % M;
      }
  printf("%d\n", w);
  return 0;
}
