program mountain;
 
const
    MAXN = 100000;
 
var
    ANS, N, i : LongInt;
    P         : Array[0..MAXN-1] of LongInt;
 
begin
{
    uncomment the two following lines if you want to read/write from files
    assign(input,  'input.txt');  reset(input);
    assign(output, 'output.txt'); rewrite(output);
}
 
    ReadLn(N);
 
    for i:=0 to N-1 do
        Read(P[i]);
    ReadLn();
 
    ANS := 0;
 
    for i:=1 to N-2 do
           if (P[i]<P[i-1]) and (P[i]<P[i+1]) then ANS:=ANS+1;
 
    WriteLn(ANS);
end.

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

NwoxIDQgMCAzIDIgNiA1Cg==

7
1 4 0 3 2 6 5