How do I stop the program from crashing after a call to the 2nd function?

the program crashes after the call to the second function from the first one. why?<br>```cpp<br>#include <iostream><br>#include <cmath><br>#include <algorithm><br>#include <fstream><br><br>using namespace std;<br><br>int main() {<br><br> string str;<br> ifstream file("input.txt");<br> if(!file.is_open()) {<br> cout << "File was not open.";<br> return 1;<br> }<br><br> string word;<br> getline(file, word);<br><br> double k1 = 0, k2 = 0;<br><br> for (int i = 0; i < word.length(); i++) {<br> k1 += word[i];<br> k2 += pow(word[i], 2);<br> }<br><br> double Ck = pow(k1, 2) / word.length();<br><br> k2 -= Ck;<br><br> double sigma = sqrt(k2 / word.length());<br><br> double childSigma = 0, childK1 = 0, childK2 = 0;<br><br> for (int i = 0; i < 1000; i++) {<br> childK1 = 0, childK2 = 0;<br> for (int j = 0; j < 100; j++) {<br> getline(file, word);<br> for (int k = 0; k < word.length(); k++) {<br> childK1 += word[k];<br> childK2 += pow(word[k], 2);<br> }<br> }<br><br> childK1 /= 100; childK2 /= 100;<br><br> childSigma = sqrt((childK2 - pow(childK1, 2)));<br><br> cout << sigma - childSigma << endl;<br> }<br><br> cout << sigma << endl;<br> cin >> str;<br> return 0;<br>}<br>```<br>dear programmers, help me not to crash the program after calling the 2nd function. I'm still in the process of learning to code, any help would be appreciated.