/*
	------------------------------------------CAUTIOUS WARNING ------------------------------------------
	This is a personalised Template for Nitin under MIT Licence Act 1840 : Do not use it for own use. */
	
	
	// TASK : Atc Upsolve
	//--------------------------------HEADERS-------------------------------------------------------------//
	#include <vector>
	#include <list>
	#include <map>
	#include <set>
	#include<cmath>
	#include <queue>
	#include <deque>
	#include <stack>
	#include <bitset>
	#include <algorithm>
	#include <functional>
	#include <numeric>
	#include <utility>
	#include <sstream>
	#include <iostream>
	#include <iomanip>
	#include <cstdio>
	#include <cmath>
	#include <cstdlib>
	#include <ctime>
	#include <limits>
	#include <string>
	#include <cassert>
	#include <cstring> 
	#include <unordered_set>
	#include <unordered_map>
	using namespace std; 
	
	//-------------------------------------------------------Typedefs----------------------------------------------//  
	
	typedef long long int ll; 
	
	typedef pair<int, int> pii; 
	
	typedef pair<ll, ll> pll; 
	
	typedef pair<string, string> pss; 
	
	typedef vector<int> vi; 
	
	typedef vector<vi> vvi; 
	
	typedef vector<pii> vii; 
	
	typedef vector<ll> vl; 
	
	typedef vector<vl> vvl; 
	
	typedef unordered_set<ll> uo_s;
	
	typedef unordered_map<ll,ll> uo_m;
	  
	typedef map<ll,ll> o_m;
	double EPS = 1e-9; 
	
	int INF = 1000000005; 
	
	long long INFF = 1000000000000000005LL; 
	
	double PI = acos(-1); 
	
	int dirx[8] = { -1, 0, 0, 1, -1, -1, 1, 1 }; 
	
	int diry[8] = { 0, 1, -1, 0, -1, 1, -1, 1 }; 
	
	//---------------------------------------------------------Hash defines--------------------------------------------------//
	
	# define    PII     3.14159265358979323846
	#ifdef TESTING 
	#define DEBUG fprintf(stderr, "====TESTING====\n") 
	#define VALUE(x) cerr << "The value of " << #x << " is " << x << endl 
	#define debug(...) fprintf(stderr, __VA_ARGS__) 
	#else 
	#define DEBUG 
	#define VALUE(x) 
	#define debug(...) 
	#endif 
	
	  
	#define FOR(a, b, c) for (int(a) = (b); (a) < (c); ++(a)) 
	#define FORN(a, b, c) for (int(a) = (b); (a) <= (c); ++(a)) 
	#define FORD(a, b, c) for (int(a) = (b); (a) >= (c); --(a)) 
	#define FORSQ(a, b, c) for (int(a) = (b); (a) * (a) <= (c); ++(a)) 
	#define FORC(a, b, c) for (char(a) = (b); (a) <= (c); ++(a)) 
	#define FOREACH(a, b) for (auto&(a) : (b)) 
	#define REP(i, n) FOR(i, 0, n) 
	#define REPN(i, n) FORN(i, 1, n) 
	#define MAX(a, b) a = max(a, b) 
	#define MIN(a, b) a = min(a, b) 
	#define SQR(x) ((ll)(x) * (x)) 
	#define RESET(a, b) memset(a, b, sizeof(a)) 
	#define ff first 
	#define ss second 
	//#define mp make_pair 
	#define pb push_back 
	#define ALL(v) v.begin(), v.end() 
	#define ALLA(arr, sz) arr, arr + sz 
	#define SIZE(v) (int)v.size() 
	#define SORT(v) sort(ALL(v)) 
	#define REVERSE(v) reverse(ALL(v)) 
	#define SORTA(arr, sz) sort(ALLA(arr, sz)) 
	#define REVERSEA(arr, sz) reverse(ALLA(arr, sz)) 
	#define PERMUTE next_permutation 
	#define T(a) ll a; cin >> a;
	#define TT(t) T(t); while (t--)
	#define IOS ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	#define f(i, x, y) for(int i = x; i < y; i++)
	#define array(a)   ll a[n]; 
	#define line "\n";
	#define out cout
	#define meh <<
	#define uwu >> 
	#define transforml transform(s.begin(),s.end(),s.begin(),::tolower);
	#define transformu transform(s.begin(),s.end(),s.begin(),::toupper);
	//-------------------------------------------------TEMPLATES----------------------------------------------------------//

  
	void wiley(){
	T(n)T(x)T(t)
	
	cout<< ((n+x-1)/x)*t << endl;
	}
	
	
	int main(){
		// Fast I/O --- Vroom Vroom 
		IOS
	//	TT(t){
		
	//	read();
	
		wiley();
	// By Order of Peaky Blinders.
	//	}
		return 0;
		
	}
	


Measured memory_bytes: 3608