When I run my program it doesn't show me any error messages. The problem is, when the program asks me to type p and q (line 80-81) it stops working. When I say stops working I mean that problem when windows show you an error message and closes the program suddenly.
Ps.: Can I attach a file here? I want to attach the file I'm using to run the program.

http://www.ime.usp.b...-imagens-sujas/
I'm using the file kid.pgm as input. (I don't know if you mean it when you said input hahahah)

# include <stdio.h>
# include <string.h>
# include <stdlib.h>
# define max_name 256
# define max 500
# define valormax 255
int read_pgm(char fname[],int M[max][max],int *m,int *n,int *maxval){
FILE * arq;
int i,j,k,l,aux;
char key [128];
/* Abre o arquivo de leitura*/
arq=fopen(fname,"r");
if(arq==NULL){
  printf("Erro na abertura do arquivo %s\n",fname);
  return 0;
  }
/* Le dados do cabeçalho*/
aux=fscanf(arq,"%s", key);
if(aux!=1){
  printf("Erro na leitura do arquivo %s\n",fname);
  fclose(arq);
  return 0;
  }
if(strcmp(key,"P2")!=0){
  printf("Formato desconhecido\n");
  fclose(arq);
  return 0;
  }
aux=fscanf(arq,"%d %d %d",m,n,maxval);
if(aux!=3){
  printf("Formato incorreto\n");
  fclose(arq);
  return 0;
  }


for(i=0;i<*n;i++){
  for(j=0;j<*m;j++)
    fscanf(arq,"%d",&M[i][j]);
}
fclose(arq);
return 1;
}
int write_pgm(char fname[],int M[][max],int m,int n,int maxval){
/* Escreve no arquivo de saída*/
FILE * saida;
int i,j;
saida=fopen(fname,"r");
fprintf(saida,"P2");
fprintf(saida,"%d %d",m,n);
fprintf(saida,"%d",maxval);
for(i=0;i<n;i++){
  for(j=0;j<m;j++)
    fprintf(saida,"%d",M[i][j]);
fclose(saida);
}
return 0;
}
int main(){
FILE * arq;
FILE *saida;
char fname[max_name];
char key [128];
int m,n,maxval; /* Número de colunas, linhas e maior valor da matriz recebida*/
static int a[max][max]; /*Usada para guarda a matriz recebida e calcular a Matriz mediana*/
int aux[max]; /* Auxiliar no cálculo da mediana de cada elemento*/
int aux2,b,c,x,x1,x2,y,i,j,p,q,min; /*Auxiliares para cálculos variados em todo o programa*/
printf("Digite o nome do arquivo de entrada:\n");
scanf("%s",fname);
j=read_pgm(fname,a,&m,&n,&maxval);
if(j==0)
  return 0;
  for(i=0;i<n;i++){
    for(j=0;j<m;j++)
    printf("%d",a[i][j]);
}
printf("\n");
printf("%d %d",n,m);
printf("\n");
printf("Digite o tamanho da vizinhança (p q):");
scanf("%d %d",&p,&q);
x=p/2;
y=q/2;
/* Construção da matriz mediana*/
/* Elementos da matriz original que serão utilizados*/
for(i=0+x;i<n-x;i++){
  for(j=0+y;j<m-y;j++){
      /* "Pega" a vizinhança dos elementos */
    for(b=i-x;b<i+x;b++){
      for(c=j-y;c<j+y;c++)
        aux[b+c]=a[b][c];
    }
    /* Ordena o vetor para achar a mediana*/
    for(x1=0;x1<(p*q)-1;x1++){
      min=aux[x1];
      for(x2=(x1+1);x2<(p*q);x2++){
        if(aux[x2]<min)
          min=aux[x2];
        aux2=aux[x1];
        aux[x1]=aux[min];
        aux[min]=aux2;
        }
    }
    a[i][j]=aux[(p*q)/2];
  }
}
/* Colocando med=0 nos elementos com a vizinhança não definida*/

for(i=0;i<x;i++){
  for(j=0;j<m;j++)
    a[i][j]=0;
}
for(i=n-x;i<n;i++){
    for(j=0;j<m;j++)
      a[i][j]=0;
}
for(j=0;j<y;j++){
  for(i=0;i<n;i++)
    a[i][j]=0;
}
for(j=m-y;j<m;j++){
  for(i=0;i<n;i++)
    a[i][j]=0;
}
if(m<16&&n<16){
  for(i=0;i<n;i++){
    for(j=0;j<m;j++)
      printf("%d",a[i][j]);
  }
}
printf("Digite o nome do arquivo de saida:");
scanf("%s",fname);
write_pgm(fname,a,m,n,maxval);
return 0;
}

No, my compiler didn't show me. What must I change in my compiler? And, I was able to change the warnings 3 and 6. Do you know what can I do to change the others?
Ps.: Your last post was very very helpful but my program is still not working.

I'm sorry, I don't know if it will answer your question but I'm using codeblocks and "-Wall -ansi -pedantic -O2" that's "activated" in my Codeblocks. I hope I could answer you.

I don't have any warnings. I'm sorry but, can you explain what is wrong with the lines 129 and 39? I don't see what's wrong in this lines.

Ps.: I configured my compiler to show warnings so, i don't think the program has warnings.