main.adb:15:14: warning: subprogram "Visit_Islands" has no effect[#0]
main.adb:22:14: medium: array index check might fail (e.g. when i = 0) [possible explanation: subprogram at line 15 should mention i in a precondition][#1]
main.adb:22:17: medium: array index check might fail (e.g. when j = 6) [possible explanation: subprogram at line 15 should mention j in a precondition][#2]
main.adb:42:31: medium: overflow check might fail[#3]
