x1=c(seq(1,10),NA,seq(1,10))

x2=c(seq(1,9),NA,seq(1,11))

x3=c(seq(1,8),NA,seq(1,12))

x4=c(seq(1,7),NA,seq(1,13))

x5=c(seq(1,6),NA,seq(1,14))

dados=data.frame(x1,x2,x3,x4,x5)