{"problem":{"name":"Lucas Number","description":{"content":"It is November $18$ now in Japan. By the way, $11$ and $18$ are adjacent Lucas numbers. You are given an integer $N$. Find the $N$\\-th Lucas number. Here, the $i$\\-th Lucas number $L_i$ is defined as ","description_type":"Markdown"},"platform":"AtCoder","limit":{"time_limit":2000,"memory_limit":262144},"difficulty":"None","is_remote":true,"is_sync":true,"sync_url":null,"sign":"abc079_b"},"statements":[{"statement_type":"Markdown","content":"It is November $18$ now in Japan. By the way, $11$ and $18$ are adjacent Lucas numbers.\nYou are given an integer $N$. Find the $N$\\-th Lucas number.\nHere, the $i$\\-th Lucas number $L_i$ is defined as follows:\n\n*   $L_0=2$\n*   $L_1=1$\n*   $L_i=L_{i-1}+L_{i-2} (i≥2)$\n\n## Constraints\n\n*   $1≤N≤86$\n*   It is guaranteed that the answer is less than $10^{18}$.\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":"abc079_b","tags":[],"sample_group":[["5","11\n\n*   $L_0=2$\n*   $L_1=1$\n*   $L_2=L_0+L_1=3$\n*   $L_3=L_1+L_2=4$\n*   $L_4=L_2+L_3=7$\n*   $L_5=L_3+L_4=11$\n\nThus, the $5$\\-th Lucas number is $11$."],["86","939587134549734843"]],"created_at":"2026-03-03 11:01:14"}}