Buggy python submission (verdict: Runtime Error):
import * as fs from 'fs'

function main(input: string) {
  let lines = input.split('\n');
  let tmp = lines[0].split(' ');

  let N = Number(tmp[0]);
  let A = Number(tmp[1]);

  let x = [0];
  x = x.concat(lines[1].split(' ').map(Number));

  let dp = new Array(N + 1);
  for (let i = 0; i <= N; ++i) {
    dp[i] = new Array(N + 1);
    for (let j = 0; j <= N; ++j) {
      dp[i][j] = new Array(A * N + 1).fill(0);
    }
  }

  for (let i = 0; i < N; ++i) dp[i][0][0] = 1;

  for (let i = 1; i <= N; ++i) {
    for (let j = 1; j <= i; ++j) {
      for (let k = 1; k <= A * N; ++k) {
        if (k < x[i]) {
          dp[i][j][k] = dp[i - 1][j][k];
        } else {
          dp[i][j][k] = dp[i - 1][j][k] + dp[i - 1][j - 1][k - x[i]];
        }
      }
    }
  }

  let ans = 0;
  for (let j = 1; j <= N; ++j) {
    ans += dp[N][j][j * A];
  }

  console.log(ans);
}

main(fs.readFileSync('/dev/stdin', 'utf8').toString());

Fixed submission:
if __name__ == '__main__':
    N, A = map(int, input().split())
    x = list(map(int, input().split()))

    x.insert(0, 0)

    dp = [[[0 for _ in range(N * A + 1)] for _ in range(N + 1)] for _ in range(N + 1)]
    for i in range(N + 1):
        dp[i][0][0] = 1

    for i in range(1, N + 1):
        for j in range(1, i + 1):
            for k in range(1, N * A + 1):
                dp[i][j][k] = dp[i - 1][j][k]
                if k >= x[i]:
                    dp[i][j][k] += dp[i - 1][j - 1][k - x[i]]

    ans = 0
    for j in range(1, N + 1):
        ans += dp[N][j][A * j]

    print(ans)

Buggy python submission (verdict: Runtime Error):
def main():
    N, A = map(int, input().split())
    x = [0].extend(list(map(int, input().split())))

    dp = [[[0 for _ in range(N * A + 1)] for _ in range(N + 1)] for _ in range(N + 1)]
    for i in range(N + 1):
        dp[i][0][0] = 1

    for i in range(1, N + 1):
        for j in range(1, i + 1):
            for k in range(1, N * A + 1):
                if k < x[k]:
                    dp[i][j][k] = dp[i - 1][j][k]
                else:
                    dp[i][j][k] = dp[i - 1][j][k] + dp[i - 1][j - 1][k - x[i]]

    ans = 0
    for j in range(1, N + 1):
        ans += dp[N][j][A * j]

    print(ans)


if __name__ == '__main__':
    main()


Fixed submission:
if __name__ == '__main__':
    N, A = map(int, input().split())
    x = list(map(int, input().split()))

    x.insert(0, 0)

    dp = [[[0 for _ in range(N * A + 1)] for _ in range(N + 1)] for _ in range(N + 1)]
    for i in range(N + 1):
        dp[i][0][0] = 1

    for i in range(1, N + 1):
        for j in range(1, i + 1):
            for k in range(1, N * A + 1):
                dp[i][j][k] = dp[i - 1][j][k]
                if k >= x[i]:
                    dp[i][j][k] += dp[i - 1][j - 1][k - x[i]]

    ans = 0
    for j in range(1, N + 1):
        ans += dp[N][j][A * j]

    print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
if __name__ == '__main__':
    N, A = map(int, input().split())
    x = list(map(int, input().split()))

    # x.insert(0, 0)

    dp = [[[0 for _ in range(N * A + 1)] for _ in range(N + 1)] for _ in range(N + 1)]
    for i in range(N + 1):
        dp[i][0][0] = 1

    for i in range(1, N + 1):
        for j in range(1, i + 1):
            for k in range(1, N * A + 1):
                dp[i][j][k] = dp[i - 1][j][k]
                if k >= x[i - 1]:
                    dp[i][j][k] += dp[i - 1][j - 1][k - x[i - 1]]

    ans = 0
    for j in range(1, N + 1):
        ans += dp[N][j][A * j]

    print(ans)


Fixed submission:
if __name__ == '__main__':
    N, A = map(int, input().split())
    x = list(map(int, input().split()))

    x.insert(0, 0)

    dp = [[[0 for _ in range(N * A + 1)] for _ in range(N + 1)] for _ in range(N + 1)]
    for i in range(N + 1):
        dp[i][0][0] = 1

    for i in range(1, N + 1):
        for j in range(1, i + 1):
            for k in range(1, N * A + 1):
                dp[i][j][k] = dp[i - 1][j][k]
                if k >= x[i]:
                    dp[i][j][k] += dp[i - 1][j - 1][k - x[i]]

    ans = 0
    for j in range(1, N + 1):
        ans += dp[N][j][A * j]

    print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
if __name__ == '__main__':
    N, A = map(int, input().split())
    x = list(map(int, input().split()))

    x.insert(0, 0)

    dp = [[[0 for _ in range(N * A + 1)] for _ in range(N + 1)] for _ in range(N + 1)]
    for i in range(N + 1):
        dp[i][0][0] = 1

    for i in range(1, N + 1):
        for j in range(1, i + 1):
            for k in range(1, N * A + 1):
                dp[i][j][k] = dp[i - 1][j][k]
                if k >= x[i]:
                    dp[i][j][k] += dp[i - 1][j - 1][k - x[i]]

    ans = 0
    for j in range(1, N + 1):
        ans += dp[N][j][A * j]

    print(ans)


Fixed submission:
if __name__ == '__main__':
    N, A = map(int, input().split())
    x = list(map(int, input().split()))

    x.insert(0, 0)

    dp = [[[0 for _ in range(N * A + 1)] for _ in range(N + 1)] for _ in range(N + 1)]
    for i in range(N + 1):
        dp[i][0][0] = 1

    for i in range(1, N + 1):
        for j in range(1, i + 1):
            for k in range(1, N * A + 1):
                dp[i][j][k] = dp[i - 1][j][k]
                if k >= x[i]:
                    dp[i][j][k] += dp[i - 1][j - 1][k - x[i]]

    ans = 0
    for j in range(1, N + 1):
        ans += dp[N][j][A * j]

    print(ans)