iscr_97 <- array(c(181,146,245),dim=c(3,1))
iscr_98 <- array(c(154,126,140),dim=c(3,1))
ripe_97 <- array(c(81,38,48),dim=c(3,1))
ripe_98 <- array(c(36,35,37),dim=c(3,1))
totale <- array(c(iscr_97,rip_97,iscr_98,rip_98),dim=c(3,4)); totale
     [,1] [,2] [,3] [,4]
[1,]  181   81  154   36
[2,]  146   38  126   35
[3,]  245   48  140   37
abband_1_2 <- totale[1,1]-totale[1,4]-totale[2,3]+totale[2,4]; abband_1_2
[1] 54
abband_2_3 <- totale[2,1]-totale[2,4]-totale[3,3]+totale[3,4]; abband_2_3
[1] 8