input p$;
input q$;
input F$;
input x1,y2,x2,y2;
input h;
n:=(x2-x1)/h
if int(n)=n then l1;
n:=int(n)+1;
h:=(x2-x1)/n;
print h;
label l1;
n:=n+1;
dim a(n,3),b(n),y(n),s(n),r(n);
x:=x1;
r(1):=0;
r(n):=0;
for i:=2 to n-1
v:=x+h;
a(i,1):=1-h*val(p$)/2;
a(i,2):=-(2-h*h*val(q$));
a(i,3):=1+h*val(p$)/2;
b(i):=h*h*valf$);
r(i):=0;
bext i;
x:=x1;
a(1,1):=0;
a(1,2):=-(2-h*h*val(q$));
a(1,3):=1+h*val(p$)/2;
b(1):=h*h*val(f$)-(1-h*val(p$)/2)*y1;
x:=x2;
a(n,1):=1-h*val(p$)/2;
a(n,2):=-(2-h*h*val(q$));
a(n,3):=0;
b(n):=h*h*val(f$)-(1+h*val(p$)/2)*y2;
s(1):=0;
for i:=2 to n;
s(i):=b(i-1);
for j:=i-2 to i-1;
if j<1 or j>n then l2;
s(i):=s(i)-s(j)*a(i-1,j-i+3);
label l2;
next j;
s(i):=s(i)/a(i-1,3);
next i;
y(1):=1;
for i:=2 to n;
y(i):=b(i-1);
for j:=i-2 to i-1;
if j<1 or j>n then l3;
y(i):=y(i)-y(j)*a(i-1,j-i+3);
label l3;
next j;
y(i):=y(i)/a(i-1,3);
r(i):=y(i)-s(i);
next i;
w:=b(n)-a(n,1)*s(n-1)-a(n,2)*s(n);
y(1):=w/(a(n,1)*r(n-1)+a(n,2)*r(n));
for i:=2 to n;
y(i):=y(1)*r(i)+s(i);
next i;
end;