use std::io; use std::io::{BufRead, Write}; macro_rules! input { (stdin = $stdin:expr, $($r:tt)*) => { let s = { let mut s = String::new(); $stdin.read_to_string(&mut s).unwrap(); s }; let mut iter = s.split_whitespace(); input_inner!{iter, $($r)*} }; } macro_rules! input_inner { ($iter:expr) => {}; ($iter:expr, ) => {}; ($iter:expr, $var:ident : $t:tt $($r:tt)*) => { let $var = read_value!($iter, $t); input_inner!{$iter $($r)*} }; } macro_rules! read_value { ($iter:expr, ( $($t:tt),* )) => { ( $(read_value!($iter, $t)),* ) }; ($iter:expr, [ $t:tt ; $len:expr ]) => { (0..$len).map(|_| read_value!($iter, $t)).collect::>() }; ($iter:expr, chars) => { read_value!($iter, String).chars().collect::>() }; ($iter:expr, usize1) => { read_value!($iter, usize) - 1 }; ($iter:expr, $t:ty) => { $iter.next().unwrap().parse::<$t>().expect("Parse error") }; } #[allow(unused_macros)] macro_rules! assert_judge { ($method:ident, $input:expr, $expected:expr) => { { let input = $input.as_bytes(); let mut output = Vec::new(); $method(&input[..], &mut output); let output = String::from_utf8(output).expect("Not UTF-8"); assert_eq!($expected, output); } }; } fn main() { let stdio = io::stdin(); let input = stdio.lock(); let output = io::stdout(); process(input, output) } // 0 -> 6 // 1 -> 2 // 2 -> 5 // 3 -> 5 // 4 -> 4 // 5 -> 5 // 6 -> 6 // 7 -> 3 // 8 -> 7 // 9 -> 6 // 2 -> 1 // 3 -> 7 // 4 -> 11 // 5 -> 71 // 6 -> 111 // 7 -> 711 // odd -> 7111... // even -> 1111... fn process(mut reader: R, mut writer: W) where R: BufRead, W: Write { input! { stdin = reader, n: i32 } let n_digits_by_1 = n / 2; if n % 2 == 1 { write!(writer, "7{}", "1".repeat((n_digits_by_1 - 1) as usize)); } else { write!(writer, "{}", "1".repeat(n_digits_by_1 as usize)); } } #[cfg(test)] mod tests { use super::*; #[test] fn sample1() { assert_judge!(process, "2", "1\ "); } #[test] fn sample2() { assert_judge!(process, "3", "7\ "); } #[test] fn sample3() { assert_judge!(process, "4", "11\ "); } }