//Задание 3.199 Кучеренко

const 
    pi: real = 3.14159265359;

Begin
  var y, a, b, x, t: real;
    
  writeln('Vvedite cherez probel:');
  writeln('a, b, x, t');
  readln(a, b, x, t);
  
  if x < t then
    y := a * exp(ln(x) * b) + pi
  else
    y := x + sin(exp(ln(x) * a) - b);
    
  writeln('Y = ', y); 
end.