import java.util.Scanner;
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int N = sc.nextInt();
int L = sc.nextInt();
int D = sc.nextInt();
int[] check = new int[2000000];
int time = 0;
int answer = 0;
for(int x=0; x<N; x++) {
for(int y=0; y<L; y++) {
check[time]=1;
time++;
}
time+=5;
}
while(check[answer] ==1) {
answer+=D;
}
System.out.print(answer);
}
}