#include <bits/stdc++.h>
int a, b, c, prad[1000001];
using namespace std;
int main() {
  long long pro = 0;
  for (int i = 1; i < 1000001; ++i) {
    for (int j = 1; j * i < 1000001; ++j) {
      ++prad[j * i];
    }
  }
  cin >> a >> b >> c;
  for (int j = 1; j < a + 1; ++j)
    for (int ja = 1; ja < b + 1; ++ja)
      for (int ha = 1; ha < c + 1; ++ha) {
        pro += prad[ha * ja * j];
        long long ta = pro >> 30;
        ta << 30;
        pro = pro - ta;
      }
  cout << pro;
}
