PROGRAM nibunhou_1
!***** declaration of variables ***************************
   IMPLICIT NONE
   REAL(8) a,b,c,FXa,FXb,FXc
   REAL(8):: EPS=1.0D-10
   INTEGER I
!***** initial conditions *********************************
   a=-10.0D0
   b=10.0D0
!***** repeated calculations ******************************
   DO I=1,100
    FXa=exp(a)-1.0
    FXb=exp(b)-1.0
    c=(a+b)/2.0
    FXc=exp(c)-1.0
      if (FXa*FXc<=0) then
       b=c
     else
       a=c
     end if
     
    if(ABS(b-a)<EPS) EXIT
   end do
   write(*,*) c
 end program nibunhou_1