Vus the Cossack and Strings

#include <bits/stdc++.h>
#define uns unsigned
#define ll long long
const char newline('\n');
using namespace std;
///**************************contest setup

string a, b;
unsigned res;

int main()
{
    getline(cin, a);
    getline(cin, b);
    const int sa = a.size(), sb = b.size();
    vector <int> spa(sa + 5, 0);

    for (int i = 1; i <= sa; i++)
    {
        spa.at(i) = spa.at(i - 1) + int(a.at(i - 1) - '0');
    }

    const int nrof1 = count(b.begin(), b.end(), '1');
    for (int i = sb; i <= sa ; i++)
    {
        if (((spa.at(i) - spa.at(i - sb)) % 2) == (nrof1 % 2))
            res++;
    }

    cout << res;//*/

    return EXIT_SUCCESS;
}