第三题：
import java.util.Scanner;
public class Problem3 {
private static long pow(long number, long index) {
if (index == 0) {
return 1;
}
if (index == 1) {
return number;
}
long mid = index / 2;
long r1 = pow(number, mid);
return r1 * r1 * pow(number, index - 2 * mid);
}
private static long getDay(long x, long k) {
int day = 0;
int base = 1;
while (base <= x) {
day ++;
base *= k;
}
return day;
}
private static boolean single(long n, long k, long x) {
long days = getDay(x, k);
long res = 0;
long base = 1;
for (long i = 0; i < days; ++ i) {
res += (x / base);
base *= k;
}
return res >= n;
}
private static void solution(long n, long k) {
if (n == 1) {
System.out.println(1);
return;
}
long left = 2, right = n;
if (single(n, k, left)) {
System.out.println(2);
return;
}
while (left < right) {
//System.out.println(left + " --- " + right + " " + single(n, k, 8));
if (left + 1 == right) {
if (single(n, k, left)) {
System.out.println(left);
} else {
System.out.println(right);
}
return;
}
long mid = (left + right) / 2;
if (single(n, k, mid)) {
right = mid;
} else {
left = mid;
}
}
System.out.println(left);
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int n = scanner.nextInt(), k = scanner.nextInt();
solution(n, k);
//System.out.println(single(10, 3, 8));
}
}
