void main()
{
    int n,i,sum=0;
    clrscr();
    printf("\n PLEASE ENTER THE VALUE OF N: ");
    scanf("%d",&n);
    printf("\n\n SUM = ");
    for(i=1;i<=n;i++)
    {
        if(i%2==1)
        {
            if(i==1)
                sum=1;
            else
                sum=sum-i*i;
            if(i==n)
            printf("%d",i*i);
            else
            printf("%d + ",i*i);
        }
        else
        {
            sum=sum+i*i;
            if(i==n)
            printf("%d",i*i);
            else
            printf("%d - ",i*i);
         }
     }
     printf("\n THE SUM IS %d",sum);

     getch();
}



*************************** OUTPUT ************************


 PLEASE ENTER THE VALUE OF N: 6


 SUM = 1 + 4 - 9 + 16 - 25 + 36
 THE SUM IS 23


 PLEASE ENTER THE VALUE OF N: 7


 SUM = 1 + 4 - 9 + 16 - 25 + 36 - 49
 THE SUM IS -26


***********************************************************