Adding binary numbers with a acumulator - c++

Question

I'm doing a code that takes a text that is converted to binary, the program need to add every number converted, what I'm doing is to create an acumulator to add all the numbers to a single one, there are 200 binary nombers, the program goes well until the 18 iteration
The libraries:
#include <iostream>
#include <math.h>
#define MAX 200
#include <bitset>
#include <stdlib.h>
#include <sstream>
This is the main:
int main()
{
bitset<8>text[MAX];
string myString = "2074656d7075732e20446f6e65632076697461652073617069656e207574206c696265726f2076656e656e617469732066617563696275732e204e756c6c616d207175697320616e74652e20457469616d2073697420616d6574206f7263692065676574";
for (std::size_t i = 0; i < myString.size(); ++i){
text[i]=bitset<8>(myString.c_str()[i]);
}
int array[20];
int i=0;
long acumulator=0;
bool f=0;
for(int j=0;j<18;j++){
if(f==0){
string b = text[j].to_string();
long bn1 = atoi(b.c_str());
acumulator = add(bn1,0);
f=1;
}else{
string b = text[j].to_string();
long bn1 = atoi(b.c_str());
acumulator = add(bn1,acumulator);
}
}
cout<<acumulator;
return 0;
}
I convert the string into binary and save them into an array, then I call the "add" function, if its the first iteration, add the first number with a 0 and save the result in a var called "acumulator", then continue calling the function with the next number and the acumulator, all works till the 18 iteration, where start to adding weird numbers
The add function:
long add(long bn1,long bn2){
int r=0, i=0;
int sum[100];
stringstream ss;
while (bn1 != 0 || bn2 != 0) {
sum[i++] = (int)((bn1 % 10 + bn2 % 10 + r) % 2);
r = (int)((bn1 % 10 + bn2 % 10 + r) / 2);
bn1 = bn1 / 10;
bn2 = bn2 / 10;
}
if (r != 0){
sum[i++] = r;
}
for (int j = i-1; j >=0; j--){
ss << sum [j];
}
long result;
ss >> result;
return result;
}
Here I do the binary add and the result is transformed into a long, and return it to use it into the next iteration
And don't know why stop working in the 18 iteration, any idea of what is happening?