#include <iostream>
#include <cstdio>
using namespace std;
int main() {
int n, k, tmp, n2, i;
scanf("%d%d", &n, &k);
tmp=n-n/k;
n2=n;
while(n2>0) {
n2=n, i=tmp;
while(i>0) n2-=i, i/=k;
if(n2>0) tmp++;
}
printf("%d", tmp);
return 0;
}
I2luY2x1ZGUgPGlvc3RyZWFtPgojaW5jbHVkZSA8Y3N0ZGlvPgp1c2luZyBuYW1lc3BhY2Ugc3RkOwoKaW50IG1haW4oKSB7CglpbnQgbiwgaywgdG1wLCBuMiwgaTsKCXNjYW5mKCIlZCVkIiwgJm4sICZrKTsKCXRtcD1uLW4vazsKCW4yPW47Cgl3aGlsZShuMj4wKSB7CgkJbjI9biwgaT10bXA7CgkJd2hpbGUoaT4wKSBuMi09aSwgaS89azsKCQlpZihuMj4wKSB0bXArKzsKCX0KCXByaW50ZigiJWQiLCB0bXApOwoJcmV0dXJuIDA7Cn0=