原式=1/4+(2+1/4)+(3+3/4)-(1+2/4)-(3+3/4)
=1/4+2+1/4+3+3/4-1-2/4-3-3/4
=(2+3-1-3)+(1/4+1/4+3/4-2/4-3/4)
=1+0=1