#include <bits/stdc++.h>
using namespace std;
long long arr[1000005] = {0}, arr2[1000005] = {0};
int main() {
  int a, b, c, ch = 0;
  long long co = 0, p = 0, x = 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++) {
        arr[co] = i * j * k;
        co++;
      }
    }
  }
  co = 0;
  while (arr[co]) {
    if (arr2[arr[co]]) {
      x += arr2[arr[co]];
      co++;
      continue;
    }
    for (int i = 1; i * i <= arr[co]; i++) {
      if (arr[co] % i == 0) p++;
      if (i * i == arr[co]) {
        ch = 1;
      }
    }
    p = p * 2;
    if (ch) {
      p--;
      ch = 0;
    }
    arr2[arr[co]] = p;
    x += p;
    p = 0;
    co++;
  }
  printf("%llu", x);
  return 0;
}
