// Computing the sum of the consecutive integers from 1 to n:
long n = 10000; // ten thousand

// Algorithm A
long sum = 0;
for (long i = 1; i <= n; i++)
   sum = sum + i;
System.out.println(sum);

// Algorithm B
sum = 0;
for (long i = 1; i <= n; i++)
{
   for (long j = 1; j <= i; j++)
      sum = sum + 1;
} // end for
System.out.println(sum);

// Algorithm C
sum = n * (n + 1) / 2;
System.out.println(sum);