N6. Блок-схемы

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#include <iostream>
#include <cmath>
using namespace std;
using ll  = long long;
ll a,b;

ll S(ll x){
    return (2*3 + 3 * (x - 1)) * x / 2;
}


bool f(ll N){
    ll R = N;
    while (R >= 100){
        R = 0;
        while (N>0){
            R += (N % 100);
            N /= 100;
        }
        N = R;
    }
    if (R % 11 == 0) return true;
    else return false;
}


int main()
{
    ll cnt = 0;
    for (ll i = 1000; i <= 1500; ++i){
        if (f(i)){
            cnt++;
        }
    }
    cout<<"cnt = "<<cnt<<'\n';
}