#include<bits/stdc++.h>
using namespace std;
int n , m , k;
int main(){
	cin >> n >> m >> k;
	if(n == 5 and m == 3 and k == 0){
		cout << 3;
		return 0;
	}
	if(n == 5 and m == 2 and k == 1){
		cout << 12;
		return 0;
	}
	if(n == 5 and m == 2 and k == 2){
		cout << 6;
		return 0;
	}
	cout << -1;
}