#pragma comment(linker, "/STACK:1024000000,1024000000")

#include <cstdio>

#include <string>

#include <cstdlib>

#include <cmath>

#include <iostream>

#include <cstring>

#include <set>

#include <queue>

#include <algorithm>

#include <vector>

#include <map>

#include <cctype>

#include <cmath>

#include <stack>

#include <sstream>

#include <list>

#include <assert.h>

#include <bitset>

#include <numeric>

#define debug() puts("++++")

#define gcd(a, b) __gcd(a, b)

#define lson l,m,rt<<1

#define rson m+1,r,rt<<1|1

#define fi first

#define se second

#define pb push_back

#define sqr(x) ((x)*(x))

#define ms(a,b) memset(a, b, sizeof a)

#define sz size()

#define pu push_up

#define pd push_down

#define cl clear()

#define lowbit(x) -x&x

//#define all 1,n,1

#define FOR(i,x,n)  for(int i = (x); i < (n); ++i)

#define freopenr freopen("in.txt", "r", stdin)

#define freopenw freopen("out.txt", "w", stdout)

using namespace std;

typedef long long LL;

typedef unsigned long long ULL;

typedef pair<int, int> P;

const int INF = 0x3f3f3f3f;

const LL LNF = 1e17;

const double inf = 1e20;

const double PI = acos(-1.0);

const double eps = 1e-8;

const int maxn = 2000 + 1;

const int maxm = 2e4 + 10;

const int mod = 1073741824;

const int dr[] = {-1, 1, 0, 0, 1, 1, -1, -1};

const int dc[] = {0, 0, 1, -1, 1, -1, 1, -1};

const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"};

int n, m;

const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

inline bool is_in(int r, int c) {

  return r >= 0 && r < n && c >= 0 && c < m;

}

bool vis[maxn];

int g[maxn][maxn], mu[maxn], prime[maxn];

void Moblus(){

  mu[1] = 1;  int tot = 0;

  for(int i = 2; i <= n; ++i){

    if(!vis[i])  prime[tot++] = i, mu[i] = -1;

    for(int j = 0; j < tot; ++j){

      int t = i * prime[j];

      if(t > n)  break;

      vis[t] = 1;

      if(i % prime[j] == 0)  break;

      mu[t] = -mu[i];

    }

  }

}

int ggcd(int a, int b){

  if(!b)  return a;

  if(g[a][b])  return g[a][b];

  return g[a][b] = g[b][a] = gcd(b, a%b);

}

int solve(int n, int d, int k){

  int ans = 0;

  for(int i = 1; i <= n; ++i)

    if(ggcd(d*i, k) == 1)  ans += n / i;

  return ans;

}

int main(){

  int t;

  scanf("%d %d %d",  &n, &m, &t);

  if(n > m)  swap(n, m);

  if(n > t)  swap(n, t);

  if(t > m)  swap(m, t);

  Moblus();

  int ans = 0;

  for(int i = 1; i <= t; ++i){

    int tmp = 0;

    for(int j = 1; j <= n; ++j)  if(mu[j])

      tmp += mu[j] * solve(n/j, j, i) * solve(m/j, j, i);

    ans += t/i * tmp;

  }

  printf("%d\n", (ans%mod+mod)%mod);

  return 0;

}