{"problem":{"name":"Savings","description":{"content":"AtCoDeer has an empty piggy bank.   On the morning of the $i$\\-th day, he will put $i$ yen (Japanese currency) in it: $1$ yen on the morning of the $1$\\-st day, $2$ yen on the morning of the $2$\\-nd d","description_type":"Markdown"},"platform":"AtCoder","limit":{"time_limit":2000,"memory_limit":262144},"difficulty":"None","is_remote":true,"is_sync":true,"sync_url":null,"sign":"abc206_b"},"statements":[{"statement_type":"Markdown","content":"AtCoDeer has an empty piggy bank.  \nOn the morning of the $i$\\-th day, he will put $i$ yen (Japanese currency) in it: $1$ yen on the morning of the $1$\\-st day, $2$ yen on the morning of the $2$\\-nd day, and so on.  \nEach night, he will check the amount of money in it.  \nOn which day will he find out that his piggy bank has $N$ yen or more for the first time?\n\n## Constraints\n\n*   $1 \\le N \\le 10^9$\n*   $N$ is an integer.\n\n## Input\n\nInput is given from Standard Input in the following format:\n\n$N$\n\n[samples]","is_translate":false,"language":"English"}],"meta":{"iden":"abc206_b","tags":[],"sample_group":[["12","5\n\n*   On the $1$\\-st day, the piggy bank gets $1$ yen in the morning and has $1$ yen at night.\n*   On the $2$\\-st day, the piggy bank gets $2$ yen in the morning and has $3$ yen at night.\n*   On the $3$\\-rd day, the piggy bank gets $3$ yen in the morning and has $6$ yen at night.\n*   On the $4$\\-th day, the piggy bank gets $4$ yen in the morning and has $10$ yen at night.\n*   On the $5$\\-th day, the piggy bank gets $5$ yen in the morning and has $15$ yen at night.\n\nThus, on the $5$\\-th night, AtCoDeer will find out that his piggy bank has $12$ yen or more for the first time."],["100128","447"]],"created_at":"2026-03-03 11:01:13"}}