first and last pos _ binary search

#include<bits/stdc++.h>
using namespace std;

int key ;

int first_pos(int * a, int n, const int *key  ){
    int res =-1 ;
    int l=0, r=n-1;

    while ( l<= r ){
        int mid = (l+r)/2;
        if ( a[mid]== *key ){
            res= mid;
            r=mid-1;
        }
        else if ( *key > a[mid] ){
            l=mid+1;
            continue;
        }
        else{
            r=mid-1;
            continue ;
        }
    }
    return res;
}

int last_pos(int *a , int n, const int *key  ){

    int res=-1;
    int l =0 , r= n-1;
    while( l<=r ){
        int mid= (l+r)/2;
        if ( *key == a[mid] ){
            res=mid ;
            l=mid+1;
        }
        else if ( *key > a[mid] ){
            l=mid+1;
        }
        else {
            r=mid-1;
        }
    }
    return res;
}


int main(){
    int n;
    cin >> n;
    int *a = new int [n];
    for (int i=0;i<n;i++) cin >> a[i];
    sort(a,a+n);
    cin >> key ;
    cout<<first_pos(a,n,&key)<<endl<<last_pos(a,n,&key)<<endl;
    return 0;
}