相異なる文の種類の数（c++の場合）

#include <string>
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(void){

    vector<string> line;
    string oneString;

    while(getline(cin,oneString) ){
        if(oneString == "") break;
        line.push_back(oneString);
    }
    sort(line.begin(), line.end(),greater<string>());

    int i=0;
    int chohuku = 0;
    while(i+1 < line.size()){
        if(line[i] == line[i+1]){
            chohuku++;
        }
        i++;
    }
  
    cout << (line.size()-chohuku) << endl;
    return 0;
}