
function solution(n, stations, w) {
var answer=0;
var station_index=0;
for(var i=1; i<=n;i++){
//console.log(i)
if( i>= (stations[station_index])-w && ( i<= (stations[station_index])+w))
{
i=(stations[station_index]+w);
station_index+=1;
continue;
}
else{
answer+=1;
i+=(2*w);
}
}
return answer;
}