```/* nag_rank_ci_2var (g07ebc) Example Program.
*
* Copyright 2017 Numerical Algorithms Group.
*
* Mark 26.1, 2017.
*/

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagg07.h>

int main(void)
{
/* Scalars */
double clevel, estcl, theta, thetal, thetau, ulower, uupper;
Integer exit_status, i, m, n;
NagError fail;

/* Arrays */
double *wrk = 0, *x = 0, *y = 0;
Integer *iwrk = 0;

INIT_FAIL(fail);

exit_status = 0;
printf("nag_rank_ci_2var (g07ebc) Example Program Results\n");

/* Skip Heading in data file */
scanf("%*[^\n] %" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &n, &m);

/* Allocate memory */
if (!(wrk = NAG_ALLOC(600, double)) ||
!(x = NAG_ALLOC(n, double)) ||
!(y = NAG_ALLOC(m, double)) || !(iwrk = NAG_ALLOC(300, Integer)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
scanf(" %*[^\n] ");

for (i = 1; i <= n; ++i)
scanf("%lf", &x[i - 1]);
scanf(" %*[^\n] ");

for (i = 1; i <= m; ++i)
scanf("%lf", &y[i - 1]);
scanf(" %*[^\n] ");
scanf(" %lf%*[^\n] ", &clevel);

/* nag_rank_ci_2var (g07ebc).
* Robust confidence intervals, two-sample
*/
nag_rank_ci_2var(Nag_RCI_Approx, n, x, m, y, clevel, &theta, &thetal,
&thetau, &estcl, &ulower, &uupper, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_rank_ci_2var (g07ebc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

printf("\n");
printf(" Location estimator     Confidence Interval\n");
printf("\n");
printf("   %10.4f           ( %6.4f , %6.4f )\n", theta, thetal, thetau);
printf("\n");
printf(" Corresponding Mann-Whitney U statistics\n");
printf("\n");
printf(" Lower : %8.2f\n Upper : %8.2f\n", ulower, uupper);
END:
NAG_FREE(wrk);
NAG_FREE(x);
NAG_FREE(y);
NAG_FREE(iwrk);
return exit_status;
}
```