#include <bits/stdc++.h>
using namespace std;
int d[1000005];
int main() {
  int i, j, k, a, b, c, n, s = 0;
  cin >> a >> b >> c;
  n = a * b * c;
  for (i = 1; i <= n; i++) {
    for (j = i; j <= n; j += i) {
      d[j]++;
    }
  }
  for (i = 1; i <= a; i++) {
    for (j = 1; j <= b; j++) {
      for (k = 1; k <= c; k++) {
        s = (s + d[i * j * k]) % 1073741824;
      }
    }
  }
  cout << s << "\n";
  return 0;
}
