My code is correct and returns correct answer locally, but it gets wrong answer on Codeforces.

#include<bits/stdc++.h>
using namespace std;

int main(){
  int g;
  vector<string> s;
  int grps;
  string l;

  cin >> g;
  while(g--){
    cin >> l;
    s.push_back(l);
  }

  for(int i = 0; i < s.size()-1; i++){
    if(s[i] != s[i+1])
      grps++;
  }
  cout << grps++ << endl;
}