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I saw other topics and tested with their entrances ,my program solved all of them , but I receive WA. What is wrong ?

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

char aux[21];
int excuse_maior[2][20];

void limpa_aux()
{
for(int p=0;p<21;p++)
aux[p]='\0 ...