bianry search

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

int binary(int n)
{
    int low,high,mid;
    low=0;
    high=v.size()-1;
    while(high>=low)
    {
        mid=(high+low)/2;
        if(v[mid]<=n && v[mid+1]>n){
            return v[mid];

        }
        else if(v[mid]>n)
        {
            high=mid-1;
        }
        else
        {
            low=mid+1;
        }
    }
}

int main()
{
    int n,i,k;

    for(i=2;i<=100;i+=2)
        v.push_back(i);
    scanf("%d",&n);

    k=binary(n);
    cout<<k<<endl;
    return 0;

}