#include <bits/stdc++.h>
int div(int n);
using namespace std;
map<int, int> di;
int main(int argc, char *argv[]) {
  int m = 1073741824;
  int a, b, c, i, j, k;
  long long int cnt = 0;
  scanf("%d", &a), scanf("%d", &b), scanf("%d", &c);
  for (i = 1; i <= a; i++) {
    for (j = 1; j <= b; j++) {
      for (k = 1; k <= c; k++) {
        cnt = (cnt + div(i * j * k)) % m;
      }
    }
  }
  printf("%I64d\n", cnt);
  return 0;
}
int div(int n) {
  if (di[n] > 0) {
    return di[n];
  }
  int i = 1, cnt = 0;
  int limit = (int)sqrt(n);
  for (i = 1; i <= limit; i++) {
    if (n % i == 0) {
      cnt = cnt + 2;
    }
  }
  if ((limit * limit) == n) cnt--;
  di[n] = cnt;
  return cnt;
}
