source: CIVL/mods/dev.civl.com/doc/manual/sum/sum.cvl@ 1aaefd4

#include <assert.h>
#include <stdio.h>
#ifdef _CIVL
#include <civlc.cvh>
$input int B=5, N;
$assume(1<=N && N<=B);
#else
#define N 100
#endif
int sum=0;
int main() {
  for (int i = 1; i <= N; i++) sum += i;
  printf("N=%d, sum = %d\n", N, sum);
  assert(sum == (N+1)*N/2);
}