#include <bits/stdc++.h>
const int INF = 0x3f3f3f3f;
using namespace std;
const int N = 1e6;
long long sum[N];
int i, j, k;
int a, b, c;
long long ans;
void Find() {
  for (int i = 1; i <= N; i++)
    for (int j = i; j <= N; j += i) sum[j]++;
}
int main() {
  long long int n;
  Find();
  while (~scanf("%d %d %d", &a, &b, &c)) {
    ans = 0;
    for (i = 1; i <= a; i++) {
      for (j = 1; j <= b; j++) {
        for (k = 1; k <= c; k++) {
          ans += sum[i * j * k];
        }
      }
    }
    printf("%lld\n", ans);
  }
  return 0;
}
