Составить алгоритм, вычисляющий сумму первых n нечётных натуральных чисел. n вводится с клавиатуры.

#include <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <algorithm>
#include <functional>
#include <cstring>
#include <utility>
#include <bitset>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <climits>typedef unsigned long long ulol;
typedef long long lol;
typedef long int  li;#define mp          make_pair
#define F           first
#define S           second
#define sqr(a)      ( (a) * (a) )
#define pb          push_back
#define INF         999999999
#define ret(a)      cout << endl; system("pause"); return(a)
//#define ret(a)      return(a)using namespace std;int main()
{
    string s, ans;
    cin >> s;
    for(int i = 0 ; i < s.size() ; i ++)
        if( s[i] != '1' )
            ans.pb( s[i] );
    cout << ans;
    ret(0);
}

#include <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <algorithm>
#include <functional>
#include <cstring>
#include <utility>
#include <bitset>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <climits>typedef unsigned long long ulol;
typedef long long lol;
typedef long int  li;#define mp          make_pair
#define F           first
#define S           second
#define sqr(a)      ( (a) * (a) )
#define pb          push_back
#define INF         999999999
#define ret(a)      cout << endl; system("pause"); return(a)
//#define ret(a)      return(a)using namespace std;int main()
{
    lol n;
    cin >> n;
    vector<lol> ar(n);
    for(int i = 0 ; i < n ; i ++)
        cin >> ar[i];
    for(int i = 0 ; i < n ; i += 3)
        cout << i+1 << '-' << i+3 << ": " << ar[i]+ar[i+1]+ar[i+2] << endl;
    ret(0);
}