#include <bits/stdc++.h>
using namespace std;
int num_div(int a) {
  int c = 0, sq = sqrt(a);
  for (int i = 1; i <= sq; i++) {
    if (a % i == 0) c += 2;
  }
  if (sq * sq == a) c--;
  return c;
}
int main() {
  int a, b, c, sum = 0, mod = 0, l = 1073741824;
  cin >> a >> b >> c;
  for (int i = 1; i <= a; i++) {
    for (int j = 1; j <= b; j++) {
      for (int k = 1; k <= c; k++) {
        mod = i * j * k;
        sum += num_div(mod);
        sum %= l;
      }
    }
  }
  cout << sum;
}
