var n,m,p,on_the_line,left_up,right_up,ans:longint; function gcd(a,b:longint):longint; begin if a mod b=0 then exit(b); exit(gcd(b,a mod b)); end; begin assign(input,'fence9.in'); assign(output,'fence9.out'); reset(input); rewrite(output); readln(n,m,p); if n=0 then left_up:=m else left_up:=gcd(n,m); if abs(n-p)>0 then right_up:=gcd(abs(n-p),m) else right_up:=m; on_the_line:=left_up+right_up+p; ans:=(p*m-on_the_line) div 2+1; writeln(ans); close(input); close(output); end.
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