题目链接:Codeforces 492A Vanya and Cubes
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int main () {
int n, s = 0;
scanf("%d", &n);
for (int i = 1; i; i++) {
s += i;
if (n < s) {
printf("%d\n", i - 1);
break;
} else
n -= s;
}
return 0;
}