param n := 250000;
var x{1..n} := -1;
s.t. f{i in 1..n} : if (i==1) then -2*x[i]^2+3*x[i]-2*x[i+1]+3*x[n-4]-x[n-3]
                  -x[n-2]+0.5*x[n-1]-x[n]+1
else if (i==n) then -2*x[i]^2+3*x[i]-x[i-1]+3*x[n-4]-x[n-3]-x[n-2]
                  +0.5*x[n-1]-x[n]+1 else
-2*x[i]^2+3*x[i]-x[i-1]-2*x[i+1]+3*x[n-4]-x[n-3]-x[n-2]+0.5*x[n-1]-x[n]+1 = 0;