#include <cassert>
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>

#include <ccomplex>
#include <cfenv>
#include <cinttypes>
//#include <cstdalign>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cwchar>
#include <cwctype>

#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>

#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>

using namespace std;
typedef unsigned int uint;
typedef long long int ll;
typedef unsigned long long int ull;

#define debugv(v) printf("L%d %s => ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;
#define debugm(m) printf("L%d %s is..\n",__LINE__,#m);for(auto v:m){for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) printf("L%d %s is => ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;
#define debugaa(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[x][y]<<" ";}cout<<endl;}
#define debugaar(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}
#define ALL(v) (v).begin(),(v).end()
#define BIGINT 0x7FFFFFFF
#define E107 1000000007ll
void printbit(int u) { if (u == 0)cout << 0; else { int s = 0, k = 0; for (; 0<u; u >>= 1, k++)s = (s << 1) | (u & 1); for (; 0<k--; s >>= 1)cout << (s & 1); } }

#define TIME chrono::system_clock::now()
#define MILLISEC(t) (chrono::duration_cast<chrono::milliseconds>(t).count())

namespace {
    std::chrono::system_clock::time_point t;
    void tic() { t = TIME; }
    void toc() { fprintf(stderr, "TIME : %lldms\n", MILLISEC(TIME - t)); }
    std::chrono::system_clock::time_point tle = TIME;
#ifdef __MAI
    void safe_tle(int msec) { assert(MILLISEC(TIME - tle) < msec); }
#else
#define safe_tle(k) ;
#endif
}

template<typename T1, typename T2>
ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << "(" << p.first << ":" << p.second << ")"; return o; }


random_device noize;   // noize
mt19937 mt(noize());

int rand_int(int l, int h) {
    uniform_int_distribution<> range(l, h);
    return range(mt);
}

namespace {
    class MaiScanner {
    public:
        template<typename T>
        void input_integer(T& var) {
            var = 0;
            T sign = 1;
            int cc = getchar_unlocked();
            for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc&&cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var*sign;
        }
        void ign() { getchar_unlocked(); }
        MaiScanner& operator>>(int& var) {
            input_integer<int>(var);
            return *this;
        }
        MaiScanner& operator>>(long long& var) {
            input_integer<long long>(var);
            return *this;
        }
    };
    class MaiPrinter {
        int stack_p;
        char stack[32];
    public:
        template<typename T>
        void output_integer(T var) {
            if (var == 0) {
                putchar_unlocked('0');
                return;
            }
            if (var < 0) {
                putchar_unlocked('-');
                var = -var;
            }
            stack_p = 0;
            while (var) {
                stack[stack_p++] = '0' + (var % 10);
                var /= 10;
            }
            while (stack_p)
                putchar_unlocked(stack[--stack_p]);
        }
        MaiPrinter& operator<<(char c) {
            putchar_unlocked(c);
            return *this;
        }
        MaiPrinter& operator<<(int var) {
            output_integer<int>(var);
            return *this;
        }
        MaiPrinter& operator<<(long long var) {
            output_integer<long long>(var);
            return *this;
        }
    };
}
MaiScanner scanner;
MaiPrinter printer;

/* ============ */

int n, m, kei;
int width, height;

int field[111][111];
int gx, gy;

//pair<double,int> kuri[111];
int kurix[111];
int kuriy[111];
int kuric[111];

int main() {
    int i, j, k;
    int x, y, z;
    int a, b, c, d;

    scanner >> gx >> gy >> n >> kei;
    ++gx; ++gy;

    for (i = 0; i < n; ++i) {
        scanner >> a >> b >> c;
        kurix[i] = a;
        kuriy[i] = b;
        kuric[i] = c;
    }

    for (i = 0; i <= 105; ++i) {
        field[0][i] = 0x7FFFFFFF;
        field[i][0] = 0x7FFFFFFF;
    }

    // for (y = 1; y <= 100; ++y) {
    //     for (x = 1; x <= 100; ++x) {
    //         k = min(field[y - 1][x] + kei, field[y][x - 1] + kei);
    //         for (i = 0; i < n; ++i) {
    //             if (0 < x - kurix[i] && 0 < y - kuriy[i]) {
    //                 k = min(k, field[y - kuriy[i]][y + kurix[i]] + kuric[i]);
    //             }
    //         }
    //         field[y][x] = k;
    //     }
    // }
    cout << field[gy][gy] << endl;


    return 0;
}