function A=area1_input(N)

a=0;    % lower limit
b=5.0;  % upper limit
del_x=(b-a)/N;  %the sub-interval

x(1)=a;   % a=0
F(1)=x(1)*del_x;

for i=[2:N]
  x(i)=x(i-1)+del_x;
  F(i)=F(i-1)+x(i)*del_x;
end

A=F(N);
    
return

end