{"raw_statement":[{"iden":"problem statement","content":"There is a kangaroo at coordinate $0$ on an infinite number line that runs from left to right, at time $0$. During the period between time $i-1$ and time $i$, the kangaroo can either stay at his position, or perform a jump of length exactly $i$ to the left or to the right. That is, if his coordinate at time $i-1$ is $x$, he can be at coordinate $x-i$, $x$ or $x+i$ at time $i$. The kangaroo's nest is at coordinate $X$, and he wants to travel to coordinate $X$ as fast as possible. Find the earliest possible time to reach coordinate $X$."},{"iden":"constraints","content":"*   $X$ is an integer.\n*   $1≤X≤10^9$"},{"iden":"input","content":"The input is given from Standard Input in the following format:\n\n$X$"},{"iden":"sample input 1","content":"6"},{"iden":"sample output 1","content":"3\n\nThe kangaroo can reach his nest at time $3$ by jumping to the right three times, which is the earliest possible time."},{"iden":"sample input 2","content":"2"},{"iden":"sample output 2","content":"2\n\nHe can reach his nest at time $2$ by staying at his position during the first second, and jumping to the right at the next second."},{"iden":"sample input 3","content":"11"},{"iden":"sample output 3","content":"5"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}