My Code in C doesn't work at average word length challenge

Question

#include <stdio.h>
int main() {
char ar[50];
fgets(ar,50,stdin);
int i,spaces=0,letters=0;
for(i=0;ar[i]!='\0';i++){
if((ar[i]<=122 && ar[i]>=97)||(ar[i]<=90 && ar[i]>=65)){
letters++;
}
if(ar[i]==' '){
spaces++;
}
}
int div=letters/(spaces+1);
if(letters%(spaces+1)==0){
printf("%d",div);
}
else if(letters%(spaces+1)>0){
printf("%d",div+1);
}
return 0;
}
This code doesn't work in Average Word Length Challenge but why? It fails at 5ᵗʰ case.

Answer 1

The length of the 5th test case is greater than 50. Use "char ar[70];" and "fgets(ar,70,stdin);", for example.