UVALive Great Deceiver

#include <stdio.h>
#include <math.h>
#define LL long long 

LL a[100005];
int main()
{
    LL n, k;
    int i, j;
    while(~scanf("%lld %lld", &n, &k))
    {
        int Len = 0;
        while(n) a[Len++] = n % k, n /= k;
        if(Len % 2 == 0)
        {
            LL ans = pow(k, Len/2);
            printf("%lld\n", ans);
            continue;
        }
        i = Len - 2;
        for(int flag = 1; i >= 1 && flag; i -= 2)
        {
            if(a[i])
            {
                for(j = i-1; j >= 0; j -=2)
                {
                    a[j] = k-1; 
                    flag = 0;
                }
            }
        }
        LL ans = 0, mul = 1;
        for(i = 0; i < Len; i += 2)
        {
            ans += mul * a[i];
            mul *= k;
        } 
        printf("%lld\n", ans+1);
    }
    return 0;
}