#include <bits/stdc++.h>
using namespace std;
long long sum = 0;
long long w[1100000] = {0};
long long solve(int a) {
  long long cnt = 0;
  long long t = sqrt(a);
  for (int i = 1; i <= t; i++) {
    if (a % i == 0) {
      if (a / i == i)
        cnt++;
      else
        cnt += 2;
    }
  }
  return cnt;
}
int main(void) {
  int a, b, c;
  scanf("%d %d %d", &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 q = i * j * k;
        if (!w[q]) {
          w[q] = solve(q);
        }
        sum += w[q];
        sum %= 1073741824;
      }
    }
  }
  printf("%d\n", sum);
  return 0;
}
