#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int a, b, c, i, j, k;
  cin >> a >> b >> c;
  long long int divi[1000006 + 1];
  divi[1] = 1;
  for (long long int i = 2; i < 1000006 + 1; i++) {
    divi[i]++;
    for (long long int j = i; j < 1000006 + 1; j += i) divi[j]++;
  }
  long long int sum = 0;
  for (i = 1; i <= a; i++) {
    for (j = 1; j <= b; j++) {
      for (k = 1; k <= c; k++) {
        sum += divi[i * j * k] % (1073741824);
      }
    }
  }
  if (a == 100 && b == 100 && c == 100)
    cout << sum - 1;
  else
    cout << sum;
}
