Go: package main

import (
    "bufio"
    "fmt"
    "strconv"
    "os"
    "strings"
    "math"
)

var rdr = bufio.NewReaderSize(os.Stdin, 1000000)

func readLine() string {
    buf := make([]byte, 0, 1000000)
    for {
        l, p, e := rdr.ReadLine()
        if e != nil {
            panic(e)
        }
        buf = append(buf, l...)
        if !p {
            break
        }
    }
    return string(buf)
}

func toInt(str string) int {
    n, _ := strconv.Atoi(str)
    return n
}

func abs(a int) int {
    return int(math.Abs(float64(a)))
}

func main() {
    wh := strings.Split(readLine(), " ")
    w := toInt(wh[0])
    h := toInt(wh[1])
    readLine()
    pString := strings.Split(readLine(), " ")
    var x1 [300]int
    var y1 [300]int
    var x2 [300]int
    var y2 [300]int
    cnt := 0
    for i := 0; i <= w - 1; i++ {
        x1[cnt] = i
        y1[cnt] = 0
        cnt ++
    }
    for i := 1; i <= h - 1; i++ {
        x1[cnt] = w - 1
        y1[cnt] = i
        cnt ++
    }

    for i := w - 2;i >= 0; i-- {
        x1[cnt] = i
        y1[cnt] = h - 1
        cnt ++
    }
    cnt = 0
    for i := 0; i <= w - 2; i++ {
        x2[cnt] = i
        y2[cnt] = 1
        cnt ++
    }
    for i := 2; i <= h - 2; i++ {
        x2[cnt] = w - 2
        y2[cnt] = i
        cnt ++
    }

    for i := w - 3;i >= 0; i-- {
        x2[cnt] = i
        y2[cnt] = h - 2
        cnt ++
    }

    pos1 := 0
    pos2 := 0
    ans := 0
    for _, value := range pString {
        p := toInt(value)
        if p == 0 {
            pos1 ++
        } else {
            pos2 ++
        }
        px1, py1 := x1[pos1], y1[pos1]
        px2, py2 := x2[pos2], y2[pos2]
        if abs(px1 - px2) + abs(py1 - py2) == 1 {
            ans ++
        }
    }
    fmt.Println(ans)
}

C++: #include<iostream>
#include<vector>

using namespace std;

int main(){
    int h,w;
    cin >> w >> h;
    int n;
    cin >> n;
    int ans = 0;
    int a = h+2*w-2;
    int b = h+2*w-6;
    while(n--){
        int p;
        cin >> p;
        if(p == 0) a--;
        else b--;
        if(a <= w-1 && b <= w-1){
            if(a == b) ans++;
        }
        if(w-1 <= b && b <= w+h-4 && w+1 <= a && a <= w+h-2){
            if(a-2 == b) ans++;
        }
        if(w+h-4 <= b && w+h <= a){
            if(a-4 == b) ans++;
        }
    }
    cout << ans << endl;
}

C++: #include <iostream>
#include <vector>
#include <cassert>

using namespace std;

int w, h, n;

bool adj(int a, int b) {
    if (0 <= a && a <= w - 2 &&
        0 <= b && b <= w - 2) {
        return a == b;
    }
    if (w - 2 <= a && a <= w - 2 + h - 3 && 
        w <= b && b <= w + h - 3) {
        return a - (w - 2) == b - w;
    }
    if (w - 2 + h - 3 <= a &&
        w + h - 1 <= b) {
        return a - (w - 2 + h - 3) == b - (w + h - 1);
    }
    assert(false);
}

int main() {
    while (cin >> w >> h >> n) {
        int a = 0, b = 0;
        int ans = 0;
        for (int i = 0; i < n; i++) {
            int p;
            cin >> p;
            if (p) b++; else a++;
            ans += adj(a, b);
        }
        cout << ans << endl;
    }
}

C++: /* template.cpp {{{ */
#include <bits/stdc++.h>
using namespace std;
 
// #define int long long
#define GET_MACRO(a, b, c, d, NAME, ...) NAME
#define REP1(n) REP2(i_, n)
#define REP2(i, n) REP3(i, 0, n)
#define REP3(i, a, b) REP4(i, a, b, 1)
#define REP4(i, a, b, s) for (long long i = (a); i < (long long)(b); i += (long long)(s))
#define RREP1(n) RREP2(i_, n)
#define RREP2(i, n) RREP3(i, 0, n)
#define RREP3(i, a, b) RREP4(i, a, b, 1)
#define RREP4(i, a, b, s) for (long long i = (b) - 1; i >= (long long)(a);  i -= (long long)(s))
#define rep(...) GET_MACRO(__VA_ARGS__, REP4, REP3, REP2, REP1)(__VA_ARGS__)
#define rrep(...) GET_MACRO(__VA_ARGS__, RREP4, RREP3, RREP2, RREP1)(__VA_ARGS__)
#define fs first
#define sc second
#define all(c) std::begin(c), std::end(c)
#define pcnt(x) __builtin_popcountll(x)
#define each(x, c) for (auto &&x : c)
#define endl "\n"
#define y0 y0_
#define y1 y1_
#define yn yn_
 
#define TMP_T template<typename T>
#define TMP_TU template<typename T, typename U>
#define TMP_Ts template<typename ...T>
#define TMP_NTs template<size_t N, typename ...T>
#define TMP_CT template<bool C, typename T = void>
 
#ifndef DEBUG
#define cerr no_output
struct NoOutput : ostream {
  TMP_T ostream &operator<<(const T &){ return *this; }
} no_output;
#endif
 
using uint = unsigned;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
TMP_T using PQL = priority_queue<T, vector<T>, greater<T>>;
TMP_T using PQG = priority_queue<T>;
TMP_CT using enable_if_t = typename enable_if<C, T>::type;
 
const ll LLINF = 1e18 + 10;
#ifndef int
const int INF = 1e9 + 10;
#else
const int INF = LLINF;
#endif
 
const int dx[] = {-1, 0, 1, 0, -1, 1, 1, -1};
const int dy[] = {0, -1, 0, 1, -1, -1, 1, 1};
 
TMP_T inline constexpr T sq(T x){ return x * x; }
TMP_TU inline T& chmin(T &x, U y){ if (x > y) x = y; return x; }
TMP_TU inline T& chmax(T &x, U y){ if (x < y) x = y; return x; }
 
TMP_NTs enable_if_t<(N >= sizeof...(T))> input_tuple(istream &, tuple<T...> &){}
TMP_NTs enable_if_t<(N < sizeof...(T))> input_tuple(istream &is, tuple<T...> &x){ is >> get<N>(x); input_tuple<N + 1, T...>(is, x); }
TMP_Ts ostream &operator>>(istream &is, tuple<T...> &x){ input_tuple<0, T...>(is, x); return is; }
TMP_TU ostream &operator>>(istream &is, pair<T, U> &x){ return is >> x.first >> x.second; }
TMP_NTs enable_if_t<(N >= sizeof...(T))> print_tuple(ostream &, const tuple<T...> &){}
TMP_NTs enable_if_t<(N < sizeof...(T))> print_tuple(ostream &os, const tuple<T...> &x){ os << (N > 0 ? " " : "") << get<N>(x); print_tuple<N + 1, T...>(os, x); }
TMP_Ts ostream &operator<<(ostream &os, const tuple<T...> &x){ print_tuple<0, T...>(os, x); return os; }
TMP_TU ostream &operator<<(ostream &os, const pair<T, U> &x){ return os << x.first << " " << x.second; }
 
#undef TMP_T
#undef TMP_TU
#undef TMP_Ts
#undef TMP_NTs
#undef TMP_CT

ll gcd(ll a, ll b){ return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b){ return a / gcd(a, b) * b; }
tuple<ll, ll, ll> extgcd(ll a, ll b){
  if (b){
    ll g, x, y;
    tie(g, x, y) = extgcd(b, a % b);
    return make_tuple(g, y, x - a / b * y);
  }
  return make_tuple(a, 1, 0);
}
ll invmod(ll a, ll m = 1000000007){
  ll g, x;
  tie(g, x, ignore) = extgcd(a, m);
  return g == 1 ? (x + m) % m : 0;
}

inline ll in(){ ll x; cin >> x; return x; }
 
struct prepare {
  prepare(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(12);
    cerr << fixed << setprecision(12);
  }
} prepare_;
/* }}} */

signed main()
{
  int w, h, n;
  int x[2] = {0, 0}, y[2] = {0, 1};
  cin >> w >> h >> n;
  int res = 0;
  rep(n){
    if (in() == 0){
      if (y[0] == 0 && x[0] < w - 1) x[0]++;
      else if (x[0] == w - 1 && y[0] < h - 1) y[0]++;
      else x[0]--;
    }
    else {
      if (y[1] == 1 && x[1] < w - 2) x[1]++;
      else if (x[1] == w - 2 && y[1] < h - 2) y[1]++;
      else x[1]--;
    }
    if (abs(x[0] - x[1]) + abs(y[0] - y[1]) == 1) res++;
  }
  cout << res << endl;
}

C++: #include<bits/stdc++.h>
using namespace std;

int main()
{
  int W, H;
  int N;

  cin >> W >> H;
  cin >> N;
  int x = W * 2 + H - 3;
  int y = (W - 1) * 2 + H - 5;
  int ret = 0;

  while(N--) {
    int P;
    cin >> P;
    if(P == 0) --x;
    else --y;

    if(x < W) {
      if(x == y) ++ret;
    } else if(x == W) {
      
    } else if(x < W + H - 2) {
      if(x == y + 2) ++ret;
    } else if(x == W + H - 2) {
    
    } else {
      if(x == y + 4) ++ret;
    }
  }
  cout << ret << endl;
}