#include <iostream>
using namespace std;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    long long a,b,s;
    cin>>a>>b>>s;
    long long ans=0;
    for(long long t=1; t<=s; t++){
        for(long long x=1; x*x<=t; x++){
            if(t%x!=0) continue;
            long long y=t/x;
            if(x<=a && y<=b) ans += (a-x+1)*(b-y+1);
            if(x!=y && x<=b && y<=a) ans += (b-x+1)*(a-y+1);
        }
    }
    cout<<ans<<endl;
    return 0;
}