C :

#include <stdio.h>

int main() {
	long long int a;
	long long int b[100];
	long long int i;
	scanf("%lld", &a);
	i = 0;
	while (a > 0) {
		b[i++] = a % 10;
		a = a / 10;
	}
	for (long long int j = 0; j < i; j++) {
		printf("%d", b[j]);
	}
	printf("\n");
	for (long long int k = i - 1; k >= 0; k--) {
		printf("%d", b[k]);
	}
}

C++ :

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
#define IOS ios::sync_with_stdio(0),cin.tie(0),cout.tie(0)

const int N = 1e5 + 10;
char s[N];
stack<char>sta;

void solve() {
//	freopen("C:\\Users\\zhang\\Desktop\\测试数据\\算法基础\\.3\\test2.in", "r", stdin);
//	freopen("C:\\Users\\zhang\\Desktop\\测试数据\\算法基础\\.3\\test2.out", "w", stdout);
	cin >> s;
	int len = strlen(s);
	for (int i = 0; i < len; i++) {
		sta.push(s[i]);
	}
	while (!sta.empty()) {
		cout << sta.top();
		sta.pop();
	}
	cout << endl;
	for (int i = 0; i < len; i++) {
		cout << s[i];
	}
	cout << endl;
}

signed main() {
	int T = 1;
//    cin>>T;
	while (T--) {
		solve();
	}
	return 0;
}

Java :

import java.util.Arrays;
import java.util.Scanner;

public class Main{
    public static void main(String[]args){
        Scanner input = new Scanner(System.in);
        long m = input.nextLong();
        String M=String.valueOf(m);
        char []k=M.toCharArray();
        for(int i=M.length()-1;i>=0;i--){
            System.out.print(k[i]);
        }
        System.out.println();
        System.out.print(Arrays.copyOf(k,M.length()));
    }
}