#include <bits/stdc++.h>
using namespace std;
const int N = 2010;
int pri[N], pri_cnt, mu[N];
bool mark[N];
void sieve() {
  int i, j;
  mu[1] = 1;
  for (i = 2; i < N; i++) {
    if (!mark[i]) {
      pri[++pri_cnt] = i;
      mu[i] = -1;
    }
    for (j = 1; j <= pri_cnt; j++) {
      int t = i * pri[j];
      if (t >= N) {
        break;
      }
      mark[t] = 1;
      if (i % pri[j] == 0) {
        mu[t] = 0;
        break;
      }
      mu[t] = -mu[i];
    }
  }
}
bool hav[N][N];
int G[N][N];
int gcd(int x, int y) {
  if (y == 0) {
    return x;
  }
  if (hav[x][y]) {
    return G[x][y];
  }
  G[x][y] = G[y][x] = gcd(y, x % y);
  hav[x][y] = hav[y][x] = 1;
  return G[x][y];
}
int main() {
  sieve();
  int a, b, c;
  scanf("%d%d%d", &a, &b, &c);
  if (b > c) {
    swap(b, c);
  }
  int x, y, z, t;
  unsigned int Ans = 0;
  for (x = 1; x <= a; x++) {
    unsigned int sum = 0;
    for (t = 1; t <= b; t++) {
      unsigned int s1 = 0, s2 = 0;
      for (y = t; y <= b; y += t) {
        if (gcd(x, y) == 1) {
          s1 += (b / y);
        }
      }
      for (z = t; z <= c; z += t) {
        if (gcd(x, z) == 1) {
          s2 += (c / z);
        }
      }
      sum += mu[t] * s1 * s2;
    }
    Ans += sum * (a / x);
  }
  printf("%u\n", Ans & 1073741823);
  return 0;
}
