#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int A,B,S;
  cin>>A>>B>>S;
  int ans = 0;
  for(int i=1;i<=S;i++){
      for(int j=1;j*j<=i;j++){
          if(i%j != 0) continue;
          if(j <= A && i/j <= B)ans += (A-j+1)*(B-i/j+1);
          if(j*j == i) continue;
          if(i/j <= A && j <= B)ans += (A-i/j+1)*(B-j+1);
      }
  }
  cout<<ans<<endl;
}