#include <bits/stdc++.h>
using namespace std;
int d[1010];
int f[1001001] = {0};
int main() {
  int a, b, c, sum = 0;
  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++) {
        int t = i * j * k, s = 1;
        if (f[t]) {
          sum = (sum + s) % 1073741824;
          continue;
        }
        memset(d, 0, sizeof(d));
        for (int e = 2; e <= 100; e++)
          while (t % e == 0) d[e]++, t /= e;
        for (int e = 2; e <= 100; e++)
          if (d[e]) s *= (d[e] + 1);
        f[t] = s;
        sum = (sum + s) % 1073741824;
      }
  cout << sum << endl;
}
