31463 segmentation fault C++

So I've been trying to determine if a statement is syntactically correct or not. For example ([]{}[]) is syntactically correct while [](} is not. Below is my code and I've been getting '31463 segmentation fault C++' this error when I run it. Also this 'warning: control may reach end of non-void function [-Wreturn-type]'.

#include <iostream>
#include "/Users/gansaikhanshur/Documents/atom/C++/Libraries/stdc++.h"
using namespace std;

ifstream f("/Users/gansaikhanshur/Documents/atom/C++/Project_Airi/data.in");
ofstream g("/Users/gansaikhanshur/Documents/atom/C++/Project_Airi/data.out");

stack<char> my_stack;
string imp;
char last_char;

char ReverseChar(char x){
  if(x == '{'){
    x = '}';
    return x;
  } else if(x == '[') {
    x = ']';
    return x;
  } else if(x == '('){
    x = ')';
    return x;
  } else if(x == '}') {
    x = '{';
    return x;
  } else if(x == ')'){
    x = '(';
    return x;
  } else if(x == ']') {
    x = '[';
    return x;
  }
}

int main(){

  cin >> imp;

  for(int i = 0; i < imp.size(); i++){
    my_stack.push(imp[i]);
  }

  last_char = my_stack.top();
  my_stack.pop();
  while(!my_stack.empty()){

    char lchar = my_stack.top();
    my_stack.pop();
    if(ReverseChar(lchar) == my_stack.top()){
      my_stack.pop();
    } else {
      cout << "Syntactically False";
    }

    if(my_stack.size() == 1){
      if(my_stack.top() == ReverseChar(last_char)){
        cout << "Syntactically Correct";
      } else {
        cout << "Syntactically False";
      }
    }
  }
}