PROGRAM BRODOVI;
VAR I,N,Z,K,P,L:INTEGER;
A:ARRAY[1..100] OF INTEGER;
BEGIN
READLN(N);
FOR I:=1 TO N DO BEGIN
READLN(A[I]);
END;
FOR I:=1 TO N DO
BEGIN
Z:=A[2]-A[1];
IF A[I] MOD Z<>1 THEN P:=P+1;
END;P:=P+1;
WRITELN(P);
END.