var n,i,s,max,st,dr,min:longint;
    v:array[1..10010] of longint;

begin
assign(input,'operatii.in');reset(input);
assign(output,'operatii.out');rewrite(output);
readln(n);
for i:=1 to n do
        read(v[i]);
for i:=1 to n do
        if (v[i]>v[i+1]) then
                max:=max+v[i]-v[i+1];
writeln(s);
close(input);close(output);
end.