PROGRAM TRIANGLE
      PARAMETER( NMAX=10000 )
      REAL Y(0:NMAX), X(0:NMAX)
      DX=1.0/NMAX
      X(0)=0.0
      DO 10 I=1,NMAX
         X(I)=X(I-1)+DX
         Y(I)=X(I)
  10  CONTINUE
      S=0.0
      DO 20 J=1,NMAX-1
         S=0.5*(Y(J)+Y(J-1))*DX+S
  20  CONTINUE
      WRITE(*,*) S
      STOP
      END