For problem statement at 0-999/600-699/610-619/615/problemA.txt this is a correct solution, but verifier at 0-999/600-699/610-619/615/verifierA.go ends with All tests passed can you fix the verifier? ```go
package main

import "fmt"

func main() {
    var n, m int
    fmt.Scan(&n, &m)
    covered := make([]bool, m+1)
    for i := 0; i < n; i++ {
        var xi int
        fmt.Scan(&xi)
        for j := 0; j < xi; j++ {
            var y int
            fmt.Scan(&y)
            if y >= 1 && y <= m {
                covered[y] = true
            }
        }
    }
    allCovered := true
    for i := 1; i <= m; i++ {
        if !covered[i] {
            allCovered = false
            break
        }
    }
    if allCovered {
        fmt.Println("YES")
    } else {
        fmt.Println("NO")
    }
}
```