#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
#define INF (1<<30)
#define INFLL (1ll<<60)
typedef pair<int, int> P;
typedef pair<int, P> E;
#define MOD (1000000007ll)
#define l_ength size

void mul_mod(ll& a, ll b){
	a *= b;
	a %= MOD;
}

void add_mod(ll& a, ll b){
	b += MOD;
	a += b;
	a %= MOD;
}

ll p[20]={0ll,9ll,99ll,999ll,9999ll,99999ll,999999ll,9999999ll,99999999ll,999999999ll,9999999999ll,99999999999ll,999999999999ll,9999999999999ll,99999999999999ll,999999999999999ll,9999999999999999ll,99999999999999999ll,999999999999999999ll};

ll count(ll x){
	ll ret=0ll,i,t,r,l;
	ret += (x/3)*4;
	ret += (x/5)*4;
	for(i=1ll; i<=18ll; ++i){
		t = 0ll;
		r = min(p[i],x);
		l = min(p[i-1],x);
		t += r-r/3-r/5+r/15;
		t -= l-l/3-l/5+l/15;
		ret += t*i;
	}
	return ret;
}

ll get(ll x){
	ll l=0ll,r=100000000000000000ll,m;
	while(r-l>1){
		m = (l+r)/2;
		if(count(m)>x){
			r = m;
		}else{
			l = m;
		}
	}
	return l;
}

char s[100];

int main(void){
	ll x,l,j,i=0,n,p;
	cin >> x;
	--x;
	n = get(x);
	l = x - count(n);
	++n;
	while(i<l+20){
		j = i;
		p = n;
		if(!(p%3)){
			s[i] = 'F';
			s[i+1] = 'i';
			s[i+2] = 'z';
			s[i+3] = 'z';
			i += 4;
		}
		if(!(p%5)){
			s[i] = 'B';
			s[i+1] = 'u';
			s[i+2] = 'z';
			s[i+3] = 'z';
			i += 4;
		}
		if(p%3 && p%5){
			while(p){
				s[i] = p%10+'0';
				p /= 10;
				++i;
			}
			reverse(s+j,s+i);
		}
		++n;
	}
	for(i=0; i<20; ++i){
		cout << s[i+l];
	}
	cout << endl;
	return 0;
}

