#include<iostream> #include<cstdio> #include<cstring> #include<climits> #include<algorithm> #define elif else if #define ll long long using namespace std; ll read() { ll o=0,w=1;char c=getchar(); while(c>'9'||c<'0') { if(c=='-') w=-1; c=getchar(); } while(c>='0'&&c<='9') { o=o*10+c-'0'; c=getchar(); } return o*w; } const int N=1000000001,M=1000000001; ll n,k[40],p; int main() { // freopen("set.in","r",stdin); // freopen("set.out","w",stdout); k[0]=1; cin>>n>>k[1]>>p; for(int i=1;k[i-1]<=n;i++) { k[i]=k[i-1]*k[1]; } ll ans=0; n--;ans=p+1; for(int i=1;k[i]-k[i-1]<=n;i++) { n-=k[i]-k[i-1]; ans+=(k[i]-k[i-1])*p; p--; if(p==0) break; } ans+=(n*p); cout<<ans-1; return 0; } /* 9 2 8 */