void foo(char source[], char destination[])
{
    int i,j;
    strcpy(destination,source);
    for(i=strlen(destination)-1; i>=0; i--)
    {
        if(destination[i]=='='&&destination[i-1]=='*')
        {
            destination[i]='*';
            destination[i-1]='=';
        }
        else if(destination[i]=='@'&&destination[i-1]=='*')
        {
            for(j=i+1; j<strlen(destination); j++)
            {
                if(destination[j]=='=')
                {
                    destination[j]='*';
                    destination[i-1]='=';
                    break;
                }
            }
        }
    }
}