Neutralisation of charges

 Problem:-

In a parallel universe, there are not just two charges like positive and negative, but there are $26$ charges represented by  $lower$ english alphabets.

Charges have a property of killing each other or in other words neutralizing each other if they are of same charge and next to each other.

You are given a string $s$ where each $s_i$ represents a charge, where $0\le i\le |s|-1$.

You need to output $size$ of final string followed by string after which no neutralizing is possible.

Sample Input

12
aaacccbbcccd

Sample Output

2
ad

Time Limit: 1

Memory Limit: 256

Source Limit:

Explanation

aaacccbbcccd -> accd -> ad

Code:-

#include<stdio.h>

char stack[100000];

long int top=-1;

int main()

{

    long int n,i;

    char str[100027];

    scanf("%ld",&n);

    scanf("%s",str);

for(i=0;str[i];i++)

    {

if(top!=-1 && str[i]==stack[top])

        {

            top--;

        }

        else

        {

            top++;

            stack[top]=str[i];

        }

    }

    printf("%ld\n",top+1);

    for(i=0;i<=top;i++)

     printf("%c",stack[i]);

    return 0;

}