import java.util.*;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();

        int A;
        int B;
        int C;
      
        A=N/X;
        B=N%X;
        if(B==0){
        	C=A*T;
        } else {
        	C=(A+1)*T;
        }
      
      
        // 出力
        System.out.println(C);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();

        int A;
        int B;
        int C;
      
        A=N/X;
        B=N%X;
        if(B==0){
        	C=A*T;
        } else {
        	C=(A+1)*T;
        }
      
      
        // 出力
        System.out.println(C);
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();

        int A;
        int B;
        int C;
      
        A=N/X;
        B=N%X;
        if(B==0){
        	C=A*T;
        } else {
        	C=(A+1)*T;
        }
      
      
        // 出力
        System.out.println(C);
    } main {
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();

        int A;
        int B;
        int C;
      
        A=N/X;
        B=N%X;
        if(B==0){
        	C=A*T;
        } else {
        	C=(A+1)*T;
        }
      
      
        // 出力
        System.out.println(C);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int X = sc.nextInt(); X sc.nextInt() sc.nextInt sc int T = sc.nextInt(); T sc.nextInt() sc.nextInt sc int A; A int B; B int C; C A=N/X A N/X N X B=N%X B N%X N X if(B==0){
        	C=A*T;
        } else {
        	C=(A+1)*T;
        } B==0 B 0 {
        	C=A*T;
        } C=A*T C A*T A T {
        	C=(A+1)*T;
        } C=(A+1)*T C (A+1)*T (A+1) A 1 T System.out.println(C) System.out.println System.out System System.out C String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();

        int A;
        int B;
        int C;
      
        A=N/X;
        B=N%X;
        if(B==0){
        	C=A*T;
        } else {
        	C=(A+1)*T;
        }
      
      
        // 出力
        System.out.println(C);
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();

        int A;
        int B;
        int C;
      
        A=N/X;
        B=N%X;
        if(B==0){
        	C=A*T;
        } else {
        	C=(A+1)*T;
        }
      
      
        // 出力
        System.out.println(C);
    }
} Main
import java.util.*;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();

        int A;
        int B;
        int C;
      
        A=N/X;
        B=N%X;
        if(B==0){
        	C=A*T;
        } else {
        	C=(A+1)*T;
        }
      
      
        // 出力
        System.out.println(C);
    }
}