[文件读写] 出现end of file during read！新手求助，这是书上的例题

 MODULE GAUSS
        CONTAINS
        SUBROUTINE SOLVE(A,B,X,N)
        IMPLICIT REAL*8(A-Z)
        INTEGER::I,K,N
        REAL*8::A(N,N),B(N),X(N)
        REAL*8::AUP(N,N),BUP(N)
        REAL*8::AB(N,N+1)
        AB(1:N,1:N)=A
        AB(:,N+1)=B
        DO K=1,N-1
          DO I=K+1,N
            TEMP=AB(I,K)/AB(K,K)
                AB(I,:)=AB(I,:)-TEMP*AB(K,:)
      END DO
    END DO
        AUP(:,:)=AB(1:N,1:N)
        BUP(:)=AB(:,N+1)
        CALL UPTRI(AUP,BUP,X,N)
        END SUBROUTINE SOLVE
        !!!!!!!!!!!!!!!!!!!!!!!
        subroutine uptri(a,b,x,n)
        IMPLICIT REAL*8(A-Z)
        INTEGER::I,J,N
        REAL*8::A(N,N),B(N),X(N)
        X(N)=B(N)/A(N,N)
        DO I=N-1,1,-1
          X(I)=B(I)
          DO J=I+1,N
          X(I)=X(I)-A(I,J)*X(J)
          END DO
          X(I)=X(I)/A(I,I)
    END DO
        END SUBROUTINE UPTRI
        END MODULE GAUSS
        PROGRAM MAIN
        USE GAUSS
        IMPLICIT REAL*8(A-Z)
        INTEGER,PARAMETER::N=4
        INTEGER::I,J
        REAL*8::A(N,N),B(N),X(N)
        OPEN(UNIT=11,FILE='FIN.TXT')
        
        OPEN(UNIT=12,FILE='FOUT.TXT')
        
    READ(11,*)
        READ(11,*)((A(I,J),J=1,N),I=1,N)
        READ(11,*)B
        CALL SOLVE(A,B,X,N)
        WRITE(12,101)X
        101 FORMAT(T5,'高斯消去法计算结果',/,T4,'X=',4(/F12.8))
        END PROGRAM MAIN