#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ld=long double;
using P=pair<ll,ll>;
using ps=pair<int,string>;
using V=vector<int>;
#define rep(i,n) for(int i=0;i<n;i++)
#define REP(i,n) for(int i=1;i<=n;i++)

ll a,b,s;

ll f(ll n){
    n=min(n,b);
    return n*(b+1)-n*(n+1)/2;
}

int main(){
    cin >> a >> b >> s;
    ll ans=0;
    REP(i,a) ans+=f(s/i)*(a-i+1);
    cout << ans << endl;
}