#include <bits/stdc++.h>

#define ll long long

using namespace std;

vector<vector<ll>> sieve(ll n){
    vector <bool> isPrime(n + 1, 1);
    isPrime[0] = isPrime[1] = 0;

    vector<vector<ll>>v(n+1);
    for(ll i = 2; i * i <= n; i++){
        if(isPrime[i]){
            for(ll j = i + i; j <= n; j += i) {
                isPrime[j] = false;
                v[j].push_back(i);
            }
        }
    }
    return v;
}

ll nod(ll n) {
    vector<ll>v;
    ll x=n;
    if (n==1) return 1;
    for (int i=2; i*i<=x; i++) {
        if (n%i==0) v.push_back(0);
        while (n%i==0) {
            n/=i;
            v.back()++;
        }
        if (n==1) break;
    }
    if (n!=1) v.push_back(1);
    ll ans=1;
    for (auto i:v) ans*=(i+1);
    return ans;
}
ll mod=1073741824;

ll add(ll a, ll b) {
    return ((a%mod)+(b%mod))%mod;
}

int main() {
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    ll a,b,c;
    cin >> a >> b >> c;
    ll ans=0;
    for (ll i=1; i<=a; i++) {
        for (ll j=1; j<=b; j++) {
            for (ll k=1; k<=c; k++) {
                ll x=nod(i*j*k);
                ans=add(ans,nod(i*k*j));
            }
        }
    }
    cout << ans << endl;
    return 0;
}

/*
 */