Wrong Answer in Permutation Shuffle

Can someone explain why this code in JAVA gives WA?

import java.io.;
import java.util.
;
class Permshuff
{
public static void main(String [] args)
{
InputReader1 reader = new InputReader1(System.in);
PrintWriter out=new PrintWriter(System.out);
int t=reader.nextInt();
while(t–>0)
{
int n=reader.nextInt();
int m=reader.nextInt();
boolean flag=true;
Integer a[]=new Integer[n];
for(int i=0;i<n;i++)
a[i]=reader.nextInt();
while(m–>0)
{
int from=reader.nextInt();
int to=reader.nextInt();
Arrays.sort(a,from-1,to);
}
for(int i=0;i<n;i++)
{
if(a[i]!=i+1)
{
flag=false;
break;
}
}
if(flag)
out.println(“Possible”);
else
out.println(“Impossible”);
out.flush();
}
out.close();
}
}
class InputReader1
{

private InputStream stream;
private byte[] buf = new byte[1024];
private int curChar;
private int numChars;

public InputReader1(InputStream stream) {
    this.stream = stream;
}

public int read() {
    if (numChars == -1)
        throw new InputMismatchException();
    if (curChar >= numChars) {
        curChar = 0;
        try {
            numChars = stream.read(buf);
        } catch (IOException e) {
            throw new InputMismatchException();
        }
        if (numChars <= 0)
            return -1;
    }
    return buf[curChar++];
}

public int nextInt() {
    int c = read();
    while (isSpaceChar(c))
        c = read();
    int sgn = 1;
    if (c == '-') {
        sgn = -1;
        c = read();
    }
    int res = 0;
    do {
        if (c < '0' || c > '9')
            throw new InputMismatchException();
        res *= 10;
        res += c & 15;
        c = read();
    } while (!isSpaceChar(c));
    return res * sgn;
}

public long nextLong() {
    int c = read();
    while (isSpaceChar(c))
        c = read();
    int sgn = 1;
    if (c == '-') {
        sgn = -1;
        c = read();
    }
    long res = 0;
    do {
        if (c < '0' || c > '9')
            throw new InputMismatchException();
        res *= 10;
        res += c & 15;
        c = read();
    } while (!isSpaceChar(c));
    return res * sgn;
}

public String next() {
    int c = read();
    while (isSpaceChar(c))
        c = read();
    StringBuilder res = new StringBuilder();
    do {
        res.appendCodePoint(c);
        c = read();
    } while (!isSpaceChar(c));
    return res.toString();
}

public String nextLine() {
    int c = read();
    //while (c != '\n' && c != '\r' && c != '\t' && c != -1)
    //c = read();
    StringBuilder res = new StringBuilder();
    do {
        res.appendCodePoint(c);
        c = read();
    } while (c != '\n' && c != '\r' && c != '\t' && c != -1);
    return res.toString();
}

public static boolean isSpaceChar(int c) {
    return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
}

}

Can you read this and try to ask again?