#include <bits/stdc++.h>
int main() {
  const int primes[25] = {2,  3,  5,  7,  11, 13, 17, 19, 23, 29, 31, 37, 41,
                          43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97};
  int pfc[101][25] = {0};
  for (int i = 1; i <= 100; ++i) {
    int ii = i;
    for (int j = 0; ii != 1 && j < 25; ++j) {
      while (ii % primes[j] == 0) {
        pfc[i][j] += 1;
        ii /= primes[j];
      }
    }
  }
  int a, b, c, answer(0);
  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 divisors = 1;
        for (int d = 0; d < 25; ++d) {
          divisors *= (1 + pfc[i][d] + pfc[j][d] + pfc[k][d]);
        }
        answer += divisors;
      }
    }
  }
  answer %= 1073741824;
  printf("%d\n", answer);
  return 0;
}
