#include <stdio.h>

int main( void)
{
  int i, sum;

  i = 1; sum = 0;  // initialize

  while( i <= 100) // ok for i = 1,2,...,100
  {
    sum += i;      // add to sum

    ++i;           // increment i
  }

  printf( "sum = %i\n", sum);

  return 0;
}

/*

sample run:

sum = 5050

*/