Number of Characters need to make a String Palindrome

#include<stdio.h>

#include<string.h>

int main(){

   

    int i=0,j,totChar=0,flag=0,c;

    char str[100];

    printf("Enter a String\n");

    scanf("%s",str);

    int len=strlen(str);

    j=len-1;

   

    while(i<j)

    {

           if(str[i]==str[j])

           {

               i++;

               j--;

              flag=1;

           }

        else

        {

            totChar++;

            i++;

            flag=0;

        }

    }

    if(flag!=1)

    totChar=len-1;

    c=totChar-1;

    printf("Total Characters required=%d\n",totChar);

   

    for(i=0;i<totChar;i++)

        str[len+i]=str[c--];

    str[len+i]='\0';

    printf("Final String of Palindrome=%s\n",str);

    return 0;

}

Input    : mada

Output : Total Characters required =1

               Final String of Palindrome = madam