Please help me find what is wrong with this code
#include<stdio.h>
#define size 10000
#define ascii 123
int main(){
int t,j;
char a[size];
char b[size];
int a1[ascii],b1[ascii];
long long int i,sum;
scanf("%d",&t);
for(j=0;j<t;j++){
sum=0;
memset(a1, 0, ascii*sizeof(*a1));
memset(b1, 0, ascii*sizeof(*b1));
scanf("%s",&a);
scanf("%s",&b);
i=0;
while(a[i] != 0){
a1[a[i]]++;
i++;
}
i=0;
while(b[i] != 0){
b1[b[i]]++;
i++;
}
for(i=65;i<123;i++){
if(a1[i]>0 && b1[i]>0){
if(a1[i]<b1[i]){
sum=sum+a1[i];
}
else{
sum=sum+b1[i];
}
}
}
printf("%lld\n",sum);
}
return 0;
}