疯狂随机数:
#include <iostream>
#include <math.h>
using namespace std;
int main() {
double n;
while (cin>>n){
int k;
k=(sqrt(1+8*n)-1)/2;
if(2*n>pow(k,2) && 2*n<=(pow(k,2)+k))cout<<k;
else cout<<k+1;
}
return 0;
}