#include<iostream>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair <int, int> pii;
typedef tuple<int, int, int> tiii;
typedef tuple<int, int, int, int> tiiii;
/*typedef set <int> si;
typedef map <int, int> mii;
typedef vector <int> vi;
typedef vector <ll> vll;
typedef vector <vector <int>> vvi;*/
#define F(i, a, b) for(int i = a; i <= (int)b; i++)
#define f(i, a, b) for(int i = a; i >= (int)b; i--)
#define F2(i, a, b) for(int i = a; i <= (int)b; i+=2)
#define f2(i, a, b) for(int i = a; i >= (int)b; i-=2)
#define wh(n) int iteration = n; while(iteration--)
#define For(t, it) for(auto it = (t).begin(); it != (t).end(); ++it)
#define IN insert
#define PB push_back
#define MP make_pair
#define MT make_tuple
#define RS resize
#define GRAF(n) vvi gr; gr.resize(n+1); vector <bool> was; was.resize(n+1, 0);

ll bin_pow(ll a, ll n){
	if(!n) return 1ll;
	if(n % 2) return a*1ll*bin_pow(a, n-1);
	ll k = bin_pow(a, n/2);
	return k*1ll*k;
}

ll log(ll n, ll a){
	if(n <= 1) return 1;
	return 1 + log(n/a, a);
}

ll sum(ll b, ll q, ll n){
	n = bin_pow(q, n) - 1;
	return b*1ll*n/(q-1);
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
        #ifdef LOCAL
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
	#endif
	ll n, a, b, mx;
	cin >> n >> a >> b >> mx;
	if(b == 1){
		cout << min(mx/a, n);
		return 0;
	}
	ll st = log(9*1ll*(mx + a/(b-1)), b);
	if(st > n) st = n;
	while(st){
		if(sum(a, b, st) <= mx) break;
		st--;
	}
	cerr << log(1, 2) << '\n' << log(2, 2) << '\n' << log(3, 2) << '\n' << log(4, 2);
	cout << st;
	return 0;
}