#include <bits/stdc++.h>
#define REP(i,n,N) for(int i=n;i<(int)N;i++)
#define RREP(i,n,N) for(int i=N-1;i>=n;i--)
#define p(s) cout<<(s)<<endl
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define F first
#define S second
typedef long long ll;
using namespace std;
const int inf=1e9+7;

ll a,b,c,n;
string s;
bool bi(ll Y){
	return (b-1)*Y/a+Y < c;
}
int main() {
	cin>>a>>b>>c;

	ll lb=0,ub=1e17;
	while(ub-lb>1){
		ll m = (ub + lb)/2;
		if(bi(m)) lb=m;
		else ub=m;

	}
	p(ub);
	return 0;
}