error "end while without corresponding" visualg

In your code, you have two se and only fimse . The fimse was missing for the first se . Your code should look like this:

algoritmo "semnome"
var
   n,i,ma,me:inteiro
inicio
   i<-0
   me<-0
   ma<-0
   enquanto (i<21) faca
      Escreval ("insira um numero inteiro:")
      leia (n)
      se n<0 entao
         me<- me+1
      senao
         se n>0 entao
            ma<-ma+1
         fimse
      fimse
      i<-i+1
   fimenquanto
   escreval ("a quantidade de numeros maiores inseridos foi:",ma)
   escreval ("e a quantidade de numeros menores inseridos foi:",me)
fimalgoritmo

The reason for the error message referring to fimenquanto is that there was a se block open, so it would be expected to be fimse . However, the compiler encountered a fimenquanto , which was not what he expected.