// you can also use imports, for example:

// import java.util.*;

// you can write to stdout for debugging purposes, e.g.

// System.out.println("this is a debug message");

class Solution1 {

public int solution1(int[] A, int X, int D) {

int x=-1; // coordinate

int z=-1; //time vaiable

if(x+D>=X-1){

z=0;

return z;

}

// Memmory variable. Initialize visted=false

Boolean[] mem=new Boolean[X];

for(int i=0;i<X;i++){

mem[i]=false;

}

// traversing with time in Array A

for(int j=0;j<A.length;j++){

//updating mem and x

if(mem[A[j]-1]==false){

mem[A[j]-1]=true;

if(x+D>=A[j]-1 && x<A[j]-1){

x=A[j]-1;

}

}

//cheaking jump

int y;

if(x+D<=X-1){

y=x+D;

}else{

y=X-1;

}

int k=y;

while(k>x){

if(mem[k]==true){

x=k;

if(x+D>=X-1 ){ //&& mem[X-1]==true

z=j;

return z;

} else{

k=x+D;

}

}else{

if(x+D>=X-1 ){//&& mem[X-1]==true

z=j;

return z;

}

k--;

}

}

}

return z;

}

public static void main(String[] args){

Solution1 sol1=new Solution1();

int X=7;//20;//7;//14;

int[] A={2,3,4,5,6,1};//{2,4,6,15,17,3,1,9,10,8,7,5,4,3,14,12,20,19,18};////{2,12,10,8,6,4};

//{4,1,3,2,1,5};

//{9,7,6,4,2,8,2,9};

int D=2;//2;//3;

System.out.println(sol1.solution1(A, X,D));

}

}