#include <bits/stdc++.h>
using namespace std;
int d[1000010];
int main() {
  int a, b, c, i, j, k, s = 0;
  for (i = 1; i <= 1000000; i++)
    for (j = i; j <= 1000000; j += i) d[j]++;
  cin >> a >> b >> c;
  for (i = 1; i <= a; i++)
    for (j = 1; j <= b; j++)
      for (k = 1; k <= c; k++) {
        s += d[i * j * k];
      }
  cout << s;
}
