C :

#include <stdio.h>
int main(){
	int n,i = 2;
	scanf("%d",&n);
	while(i < n){
		i *= 2;
	}
	if(i - n < n - i / 2)
		printf("%d",i);
	else
		printf("%d",i/2);
	
}

C++ :

#include<iostream>
using namespace std;
int main(){ 
   int n,i;
   cin>>n;
   i = 2;
   while(i < n){ 
     i = i * 2;
   }
   if(i - n < n - i / 2){ 
      cout<<i<<endl;
   }else{ 
      cout<<i / 2 <<endl;
   }
    
   return 0;
}

Python :

a=int(input())
b=[]
c=1
for i in range(1,33):
    b.append(c)
    c=c*2
for i in range(0,32):
    if(abs(b[i]-a)>=abs(b[i+1]-a) and abs(b[i+1]-a)<=abs(b[i+2]-a)):
        print(b[i+1])
        break