#![allow(unused_imports)] #![allow(non_snake_case)] use std::cmp::*; use std::collections::*; use std::io::Write; #[allow(unused_macros)] macro_rules! debug { ($($e:expr),*) => { #[cfg(debug_assertions)] $({ let (e, mut err) = (stringify!($e), std::io::stderr()); writeln!(err, "{} = {:?}", e, $e).unwrap() })* }; } fn main() { let n = read::(); let v = read_vec::(); let mut zero_poses = vec![]; let mut count = VecDeque::new(); for i in 0..n { if v[i] == 0 { zero_poses.push(i); } if v[i] > 1 { count.push_back((v[i] - 1, i)); } } let mut ans = 0; for pos in zero_poses { ans += (pos as i64 - count[0].1 as i64).abs(); count[0].0 -= 1; if count[0].0 == 0 { count.pop_front(); } } println!("{}", ans); } fn read() -> T { let mut s = String::new(); std::io::stdin().read_line(&mut s).ok(); s.trim().parse().ok().unwrap() } fn read_vec() -> Vec { read::() .split_whitespace() .map(|e| e.parse().ok().unwrap()) .collect() }