#include <iostream>
#include<bits/stdc++.h>
using namespace std;

int main() 
{
    string s; 
    cin >> s; 
    
    map< char, int > m; 
    int n, cntOdd=0; 
    char cOdd; 
    n = s.size(); 
    
    for(int i = 0; i < n; ++i)
    {
      m[s[i]]++; 
    }
    for(auto &x:m)
    {
      if(x.second % 2 == 1) 
      {
        cntOdd ++; 
        cOdd = x.first; 
        
      }
    }
    
    string s1 = "", s2 = ""; //s1-firsthalf, s2-secondhalf;  
    vector < char > v; 
    
    if(cntOdd > 1 || (cntOdd == 1 && s.size()%2 == 0)) cout << "NO SOLUTION\n" ; 
    else if(cntOdd ==1)
    {
      for(auto &x: m)
      {
        if(x.first == cOdd)
        {
          for(int i = 0; i<(x.second/2)+1; ++i)
          {
            v.push_back(x.first); 
          }
        }
      }
      for(auto &x: m){
        if(x.first != cOdd){
          for(int i = 0; i < (x.second/2); ++i){
            v.push_back(x.first); 
          }
        }
      }
      
      for(int i = v.size()-1 ; i>=1; --i){
        cout << v[i]; 
      } 
      for(int i = 0; i < v.size(); ++i)
        cout << v[i]; 
    }
    else{
      for(auto &x: m){
        for(int i = 0; i< (x.second/2); ++i){
          v.push_back(x.first); 
        }
      }
      for(int i = v.size()-1; i >= 0; --i)
        cout << v[i]; 
      for(int i = 0; i<v.size(); ++i)
        cout << v[i]; 
    }
    
    return 0;
}
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Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}