used binary search but getting one wrong answer. Can any one review my code?

#include<iostream>
#include<limits.h>
#include<algorithm>
#include<vector>
using namespace std;
 
int binary_search(int[],int,int,int);
int main() {
	int n,x,y;
	cin>>n>>x>>y;
	vector< pair<int,int> > contests(n);
	int v[x],w[y];
	for(int i=0;i<n;i++) {
		cin>>contests[i].first;
		cin>>contests[i].second;
	}
	//sort(contests.begin(),contests.end());
	for(int i=0;i<x;i++) cin>>v[i];
	for(int i=0;i<y;i++) cin>>w[i];
	sort(v,v+x);

what is the time complexity of upper_bound function used here? Is it log₂(N)? The lower_bound also has same complexity as upper_bound?