#include <bits/stdc++.h>
using namespace std;
long long d[1111111];
int main() {
  long long t, z = 0, l, i = 0, len;
  long long n, k = 0, m = 0, bam = 0, dan = 0, ans = 0;
  long long md = 1073741824, a, b, c, sum = 0;
  scanf("%lld %lld %lld", &a, &b, &c);
  for (l = 1; l < (a * b * c) + 1; l++)
    for (i = l; i <= a * b * c; i += l) d[i]++;
  for (l = 1; l < a + 1; l++)
    for (i = 1; i < b + 1; i++)
      for (k = 1; k < c + 1; k++) sum += (d[l * i * k] % md);
  printf("%lld", sum);
  return 0;
}
