Greedy Algorithm!

#include <iostream>

using namespace std;
int n;

static constexpr int coins[] = {1, 4, 16, 64};

int main(void) {
  scanf("%d", &n);
  int change = 1024 - n, ans = 0;
  for (int i = 3; i >= 0; --i) {
    while (change >= coins[i]) {
      change -= coins[i];
      ++ans;
    }
  }
  printf("%d\n", ans);
}