use std::io::Write;
use std::collections::*;

type Map<K, V> = BTreeMap<K, V>;
type Set<T> = BTreeSet<T>;
type Deque<T> = VecDeque<T>;

fn main() {
    input! {
        n: usize,
        p: i128,
        a: [i128; n],
    }
    let mut sum = 0;
    for (i, &a) in a.iter().enumerate() {
        if a + i as i64 * (a - 1) + sum > p {
            println!("{}", i);
            return;
        }
        sum += a;
    }
    println!("{}", n);
}

// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[macro_export]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

#[macro_export]
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_export]
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
// ---------- end input macro ----------

warning: unused import: `std::io::Write`
 --> answer.code:1:5
  |
1 | use std::io::Write;
  |     ^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

error[E0308]: mismatched types
  --> answer.code:16:27
   |
16 |         if a + i as i64 * (a - 1) + sum > p {
   |                           ^^^^^^^ expected `i64`, found `i128`

error[E0277]: cannot multiply `i64` by `i128`
  --> answer.code:16:25
   |
16 |         if a + i as i64 * (a - 1) + sum > p {
   |                         ^ no implementation for `i64 * i128`
   |
   = help: the trait `Mul<i128>` is not implemented for `i64`
   = help: the following other types implement trait `Mul<Rhs>`:
             <i64 as Mul>
             <i64 as Mul<&i64>>
             <&'a i64 as Mul<i64>>
             <&i64 as Mul<&i64>>

error[E0308]: mismatched types
  --> answer.code:16:16
   |
16 |         if a + i as i64 * (a - 1) + sum > p {
   |                ^^^^^^^^^^^^^^^^^^ expected `i128`, found `i64`

error[E0277]: cannot add `i64` to `i128`
  --> answer.code:16:14
   |
16 |         if a + i as i64 * (a - 1) + sum > p {
   |              ^ no implementation for `i128 + i64`
   |
   = help: the trait `Add<i64>` is not implemented for `i128`
   = help: the following other types implement trait `Add<Rhs>`:
             <i128 as Add>
             <i128 as Add<&i128>>
             <&'a i128 as Add<i128>>
             <&i128 as Add<&i128>>

error: aborting due to 4 previous errors; 1 warning emitted

Some errors have detailed explanations: E0277, E0308.
For more information about an error, try `rustc --explain E0277`.