C :

#include<stdio.h>   

int main(){  
	int x;
	scanf("%d",&x);
	
	int q = x / 1000;
	int b = x / 100 % 10;
	int s = x / 10 % 10;
	int g = x % 10;
	
	int c = g * 1000 + s * 100 + b * 10 + q;
	printf("%d",c);

	return 0; 
} 

C++ :

#include<iostream>
using namespace std;
int main(){
	int i,a,b,c,d;
	cin>>i;
	a=i/1000;
	b=i/100%10;
	c=i/10%10;
	d=i%10;
	cout<<d*1000+c*100+b*10+a;
}

Python :

a=int(input())
b=a//1000;
c=(a//100)%10;
d=(a//10)%10;
e=a%10;
print(e*1000+d*100+c*10+b)