func_code_string: #include <bits/stdc++.h>   using namespace std;   const long double PI = acos(-1);   vector<complex<double> > fft(const vector<complex<double> >& as) {     int n = (int)as.size();     int k = 0;     while ((1 << k) < n) k++;     vector<int> r(n);     r[0] = 0;     int h = -1;     for (int i = 1; i < n; i++) {       if ((i & (i - 1)) == 0) h++;       r[i] = r[i ^ (1 << h)];       r[i] |= (1 << (k - h - 1));     }     vector<complex<double> > root(n);     for (int i = 0; i < n; i++) {       double ang = 2.0 * PI * i / n;       root[i] = complex<double>(cos(ang), sin(ang));     }     vector<complex<double> > cur(n);     for (int i = 0; i < n; i++) cur[i] = as[r[i]];     for (int len = 1; len < n; len <<= 1) {       vector<complex<double> > ncur(n);       int step = n / (len << 1);       for (int pdest = 0; pdest < n;) {         for (int i = 0; i < len; i++) {           complex<double> val = root[i * step] * cur[pdest + len];           ncur[pdest] = cur[pdest] + val;           ncur[pdest + len] = cur[pdest] - val;           pdest++;         }         pdest += len;       }       cur.swap(ncur);     }     return cur;   }   vector<complex<double> > inv_fft(const vector<complex<double> >& fa) {     vector<complex<double> > res = fft(fa);     int nn = res.size();     for (int i = 0; i < nn; i++) {       res[i] /= nn;     }     reverse(res.begin() + 1, res.end());     return res;   }   vector<complex<double> > multiply(vector<complex<double> >& a,                                     vector<complex<double> >& b) {     int len = a.size() + b.size();     while (len & (len - 1)) ++len;     a.resize(len);     b.resize(len);     a = fft(a);     b = fft(b);     for (int i = 0; i < len; ++i) a[i] *= b[i];     a = inv_fft(a);     return a;   }   void create(string& s, int size, char x, int k, vector<complex<double> >& v) {     complex<double> zero(0, 0);     for (int i = 0, b = 1; i < size; i += b, b = 1) {       if (s[i] == x) {         b = 0;         v[i] = 1;         for (int j = i - 1; j >= 0 && s[j] != x && v[j] == zero && j >= i - k;              j--)           v[j] = 1;         int tmp = i;         for (++i; i < size && s[i] != x && i <= tmp + k && v[i] == zero; i++)           v[i] = 1;       }     }   }   int main() {     ios::sync_with_stdio(false), cin.tie(nullptr);     int k, a = 0, g = 0, c = 0, t = 0, n, m;     string s, s2;     cin >> n >> m >> k >> s >> s2;     for (int i = 0; i < m / 2; i++) {       swap(s2[i], s2[m - 1 - i]);     }     int size = 1;     while (size < m + n - 1) size *= 2;     vector<complex<double> > av(n), av2(m);     create(s, n,  A , k, av);     create(s2, m,  A , 0, av2);     av = multiply(av, av2);     vector<complex<double> > tv(n), tv2(m);     create(s, n,  T , k, tv);     create(s2, m,  T , 0, tv2);     tv = multiply(tv, tv2);     vector<complex<double> > gv(n), gv2(m);     create(s, n,  G , k, gv);     create(s2, m,  G , 0, gv2);     gv = multiply(gv, gv2);     vector<complex<double> > cv(n), cv2(m);     create(s, n,  C , k, cv);     create(s2, m,  C , 0, cv2);     cv = multiply(cv, cv2);     int sum = 0;     for (int i = 0; i < cv.size(); i++)       sum += ((int)(cv[i].real() + gv[i].real() + av[i].real() + tv[i].real() +                     0.3) == m);     cout << sum;     return 0;   }   