#include <bits/stdc++.h>
using namespace std;
bool factor[101] = {false};
int numDiv(int a) {
  if (a == 1) return 1;
  int i = 2;
  int cntr = 0;
  for (; i * i < a; i++) {
    if (a % i == 0) {
      cntr += 2;
    }
  }
  if (i * i == a) cntr++;
  cntr += 2;
  return cntr;
}
int main() {
  int a, b, c;
  int mod = 2 << 29;
  cin >> a >> b >> c;
  int d[1000001] = {0};
  for (int i = 1; i <= a * b * c; i++) {
    for (int j = 1; i * j <= a * b * c; j++) d[i * j]++;
  }
  long long sm = 0;
  for (int i = 1; i <= a; i++)
    for (int j = 1; j <= b; j++)
      for (int k = 1; k <= c; k++) sm += d[i * j * k];
  cout << sm << endl;
}
