capture {
forv i=1/20 {
forv j=1/20 {
display "check `i',`j'"
if el("a",`i',`j')==20 {
display "found at `i',`j'"
exit -1
}
if _rc==-1 {
// value was found
else if _rc==0 {
display "not found"
else exit _rc