param N := 4;

var x{1..N};

minimize f:
-1*x[1];

subject to cons1:
x[2] - x[1]^3 >= 0;

subject to cons2:
x[1]^2 - x[2] >= 0;

subject to cons3:
x[2] - x[1]^3 - x[3]^2 = 0;

subject to cons4:
x[1]^2 - x[2] - x[4]^2 = 0;

data;
var x:=
1	10
2	10
3	10
4	10;
solve;

display x;