#include <bits/stdc++.h>
using namespace std;
int arr[1000000];
int main() {
  int a, b, c, m, i, j, k;
  int sum = 0;
  cin >> a >> b >> c;
  m = a * b * c;
  for (i = 1; i <= m; i++) {
    for (j = i; j <= m; j += i) arr[j]++;
  }
  for (i = 1; i <= a; i++) {
    for (j = 1; j <= b; j++) {
      for (k = 1; k <= c; k++) {
        sum += arr[i * j * k];
        sum = sum % 1073741824;
      }
    }
  }
  cout << sum;
}
