PROGRAM ACTIVITY5
 
            IMPLICIT NONE
 
            INTEGER :: k, i, P, sum
 
            CHARACTER :: Flag1, Flag2
 
            DO
 
                        PRINT *, "Enter a positive integer (k):"
 
                        READ *, k
 
                        PRINT *, "Press 1 for  the sum of the integers &
      &from 1 to", k,"."
 
                        PRINT *, "Press 2 for", k,"!"
 
                        READ *, Flag1
 
                        IF (Flag1=="1") THEN
 
                                    sum=0
 
                                    DO i=1, k
 
                                                sum=sum+i
 
                                    END DO
 
                                    PRINT *, "Sum= ", sum
 
                        ELSE IF (Flag1=="2") THEN
 
                                    P=1
 
                                    DO i=1, k
                                    
                                                P=P*i
                                                
                                    END DO
 
                                    PRINT *, k, "!=", P
                        
                        ELSE
 
                                    PRINT *, "Invalid Option"
                        
                                    CYCLE
                                    
                        END IF
                        
                        PRINT *, "Continue? If not, press n or N, &
      &else press any other key."                                                
             
                        READ *, Flag2
 
                        IF ((Flag2=="n") .OR. (Flag2=="N")) THEN
 
                                    Exit
 
                        END IF
 
            END DO
 
            END PROGRAM ACTIVITY5