var f,g:text;
    aux,aux1,aux2,i,j:longint;
    rez:real;
begin
assign (f,'tunel.in');
assign (g,'tunel.out');
reset(f);
rewrite (g);
readln (f,aux,i);
for aux:=1 to i do
begin
readln (f,aux1,aux2,j);
rez:=rez+j;
end;
writeln (g,rez*i);
close(f);
close(g);
end.