#include
typedef unsigned long long ull;
int f(ull m) {
ull sum = 0;
for (int n = 1;; n++) {
sum += n * n * (3 * n + 1) / 2;
if (sum >= m)
return n;
}
}
int main(void) {
ull m;
scanf("%llu", &m);
printf("%d\n", f(m));
return 0;
}
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