String compression

#include
#include
using namespace std;

int main(){
int indx,i=0,j=0;
char a[1000];
int freq[26]={0};

cin.getline(a,1000);

int count=1;
int len=strlen(a);
while(j<len){
freq[a[j]-‘a’]++;
if(a[i]!=a[j]){
i++;
a[i]=a[j];
count++;
}
j++;

}
for(i=0;i<count;i++){
if(freq[a[i]-‘a’]==1){
cout<<a[i];
}
else{
cout<<a[i]<<freq[a[i]-‘a’];
}
}

cout<<endl;
return 0;

}

i am not able to find the mistake