#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

// mmap
#include <sys/mman.h>
// write
#include <unistd.h>
// exit
#include <stdio.h>
#include <stdlib.h>

int main() {
    int n;
    (void)scanf("%d", &n);

    int cnt = 1;
    int sum = 1;
    int l = 1;
    while (n - sum >= l) {
        ++cnt;
        sum += l++;
    }

    printf("%d\n", cnt);
    exit(0);
    return 0;
}