#include <stdio.h>
int main () {
    int i, m, sum=0;
    printf("Please enter a number: ");
    scanf("%d", &m);
    for(i=2;i<m;i++){
        sum+=(i-1)*i;
        if(sum>m) break;
    }
    printf("The \'n\' is: %d\n",i-1);
    return 0;
}