function solution(routes) {        
    routes.sort((a,b) => a[0] - b[0]);
    let compare = routes[0];
    let ans = 1;
    
    for(let i=1; i<routes.length; i++){
        const [f1, e1] = compare;
        const [f2, e2] = routes[i];
        
        if(e1<f2){
            ans++;
            compare = [f2, e2];
        }else{
            compare = [f2, Math.min(e1,e2)];
        }
    }
      
    return ans;
}