#include<stdio.h>
long long int gcd(long long int a, long long int b)
{
	long long int r = a % b;
	while (r > 0)
	{
		a = b;
		b = r;
		r = a % b;
	}
	return b;
}
int main()
{
	long long int a, b, k;
	scanf("%lld %lld %lld", &a, &b, &k);
	long long int l = a / gcd(a, b) * b;
	long long int min, mid, max;
	min = -1;
	max = 2e18;
	while (max - min > 1)
	{
		mid = (max + min) / 2;
		if (mid / a + mid / b - mid / l < k)
			min = mid;
		else
			max = mid;
	}
	printf("%lld\n", max);
	return 0;
}