public class Main{
  static public void main(String[] args){
  	
  	 java.util.Scanner scan = new java.util.Scanner(System.in);

  	
  	int n = scan.nextInt();
    int x = scan.nextInt();
  	int t = scan.nextInt();
  	int result;
  	/*
  	int n = Integer.parseInt(args[0]);
    int x = Integer.parseInt(args[1]);
  	int t = Integer.parseInt(args[2]);
    int result;
  	*/
  	if(n%x != 0){
  		result = (((int)(n/x))+1)*t;
  		
  	}else{
  		result = ((int)(n/x))*t;
  	}
  	System.out.println(result);
  	
  }
} public class Main{
  static public void main(String[] args){
  	
  	 java.util.Scanner scan = new java.util.Scanner(System.in);

  	
  	int n = scan.nextInt();
    int x = scan.nextInt();
  	int t = scan.nextInt();
  	int result;
  	/*
  	int n = Integer.parseInt(args[0]);
    int x = Integer.parseInt(args[1]);
  	int t = Integer.parseInt(args[2]);
    int result;
  	*/
  	if(n%x != 0){
  		result = (((int)(n/x))+1)*t;
  		
  	}else{
  		result = ((int)(n/x))*t;
  	}
  	System.out.println(result);
  	
  }
} Main static public void main(String[] args){
  	
  	 java.util.Scanner scan = new java.util.Scanner(System.in);

  	
  	int n = scan.nextInt();
    int x = scan.nextInt();
  	int t = scan.nextInt();
  	int result;
  	/*
  	int n = Integer.parseInt(args[0]);
    int x = Integer.parseInt(args[1]);
  	int t = Integer.parseInt(args[2]);
    int result;
  	*/
  	if(n%x != 0){
  		result = (((int)(n/x))+1)*t;
  		
  	}else{
  		result = ((int)(n/x))*t;
  	}
  	System.out.println(result);
  	
  } main {
  	
  	 java.util.Scanner scan = new java.util.Scanner(System.in);

  	
  	int n = scan.nextInt();
    int x = scan.nextInt();
  	int t = scan.nextInt();
  	int result;
  	/*
  	int n = Integer.parseInt(args[0]);
    int x = Integer.parseInt(args[1]);
  	int t = Integer.parseInt(args[2]);
    int result;
  	*/
  	if(n%x != 0){
  		result = (((int)(n/x))+1)*t;
  		
  	}else{
  		result = ((int)(n/x))*t;
  	}
  	System.out.println(result);
  	
  } java.util.Scanner scan = new java.util.Scanner(System.in); scan new java.util.Scanner(System.in) int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan int x = scan.nextInt(); x scan.nextInt() scan.nextInt scan int t = scan.nextInt(); t scan.nextInt() scan.nextInt scan int result; result if(n%x != 0){
  		result = (((int)(n/x))+1)*t;
  		
  	}else{
  		result = ((int)(n/x))*t;
  	} n%x != 0 n%x n x 0 {
  		result = (((int)(n/x))+1)*t;
  		
  	} result = (((int)(n/x))+1)*t result (((int)(n/x))+1)*t (((int)(n/x))+1) ((int)(n/x)) n x 1 t {
  		result = ((int)(n/x))*t;
  	} result = ((int)(n/x))*t result ((int)(n/x))*t ((int)(n/x)) n x t System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main{
  static public void main(String[] args){
  	
  	 java.util.Scanner scan = new java.util.Scanner(System.in);

  	
  	int n = scan.nextInt();
    int x = scan.nextInt();
  	int t = scan.nextInt();
  	int result;
  	/*
  	int n = Integer.parseInt(args[0]);
    int x = Integer.parseInt(args[1]);
  	int t = Integer.parseInt(args[2]);
    int result;
  	*/
  	if(n%x != 0){
  		result = (((int)(n/x))+1)*t;
  		
  	}else{
  		result = ((int)(n/x))*t;
  	}
  	System.out.println(result);
  	
  }
} public class Main{
  static public void main(String[] args){
  	
  	 java.util.Scanner scan = new java.util.Scanner(System.in);

  	
  	int n = scan.nextInt();
    int x = scan.nextInt();
  	int t = scan.nextInt();
  	int result;
  	/*
  	int n = Integer.parseInt(args[0]);
    int x = Integer.parseInt(args[1]);
  	int t = Integer.parseInt(args[2]);
    int result;
  	*/
  	if(n%x != 0){
  		result = (((int)(n/x))+1)*t;
  		
  	}else{
  		result = ((int)(n/x))*t;
  	}
  	System.out.println(result);
  	
  }
} Main
public class Main{
  static public void main(String[] args){
  	
  	 java.util.Scanner scan = new java.util.Scanner(System.in);

  	
  	int n = scan.nextInt();
    int x = scan.nextInt();
  	int t = scan.nextInt();
  	int result;
  	/*
  	int n = Integer.parseInt(args[0]);
    int x = Integer.parseInt(args[1]);
  	int t = Integer.parseInt(args[2]);
    int result;
  	*/
  	if(n%x != 0){
  		result = (((int)(n/x))+1)*t;
  		
  	}else{
  		result = ((int)(n/x))*t;
  	}
  	System.out.println(result);
  	
  }
}