{programmer:mogtaba amirzade 
url http:\\www.ifjam.com
}
p5.pas 
VAR {13}
I,N:INTEGER;
S:LONGINT;
BEGIN {PROGRAM}
READLN(N);
S:=1;
I:=1;
WHILE I<=N DO
BEGIN {WHILE}
S:=S*I;
I:=I+1;
END;
WRITELN(S);
READLN
END.