If the largest value found in matrix A is less than 20, P is set to 0. Otherwise, P is set to 1. You can nest IF statements within the clauses of other IF or ELSE statements. Any number of nesting ...

The ELSE statement optionally follows the IF statement and gives an action to be taken when the IF expression is false. The expression to be evaluated is often a comparison, for example, if max (a)<20 ...