clear all;
clc;
n=input('n = ');
a=input('a = ');
b=input('b = ');
h=(b-a)/n;
for i=1:n+1
    x(i)=a+(i-1)*h;
    f(i)=x(i)^+1;
end
s=0;
for i=2:2:n
    s=s+4*f(i);
end
s1=0;
for i=3:2:n-1
    s1=s1+2*f(i);
end
sum=h/3*(f(1)+s+s1+f(n+1))