import std.stdio, std.conv, std.functional, std.string; import std.algorithm, std.array, std.container, std.range, std.typecons; import std.numeric, std.math, std.random; import core.bitop; string FMT_F = "%.10f"; static string[] s_rd; T RD(T = long)() { while(!s_rd.length) s_rd = readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; } string RDR()() { return readln.chomp; } T[] ARR(T = long)(in string str, T fix = 0) { auto r = str.split.to!(T[]); r[] += fix; return r; } size_t[] MAKE_IDX(alias less = "a < b", Range)(Range range) { auto idx = new size_t[](range.length); makeIndex!(less)(range, idx); return idx;} size_t MIN_POS(alias less = "a < b", Range)(Range range) { auto r = minPos!(less)(range); return range.length - r.length; } bool inside(T)(T x, T b, T e) { return x >= b && x < e; } long lcm(long x, long y) { return x * y / gcd(x, y); } long mod = 10^^9 + 7; //long mod = 998244353; //long mod = 1_000_003; void moda(ref long x, long y) { x = (x + y) % mod; } void mods(ref long x, long y) { x = ((x + mod) - (y % mod)) % mod; } void modm(ref long x, long y) { x = (x * y) % mod; } void main() { auto N = RD; auto M = RD; auto A = RD; auto lrp = new long[][](M, 3); foreach (i; 0..M) { lrp[i] = [RD-1, RD-1, RD]; /*if (lrp[i][0] != 0) lrp[i][2] -= A; if (lrp[i][1] != N-1) lrp[i][2] -= A;*/ } lrp.sort!"a[0] < b[0]"(); auto dp = new long[][](N+1, 2); size_t li; foreach (i; 0..N) { if (dp[i][0] > dp[i+1][0]) dp[i+1] = dp[i].dup; if (li == M) continue; while (lrp[li][0] == i) { auto r = lrp[li][1]; auto p = lrp[li][2]; if (dp[i][1] != i) p -= A; if (r != N-1) p -= A; if (dp[i][0] + p > dp[r+1][0]) { dp[r+1] = [dp[i][0]+p, r+1]; } ++li; if (li == M) break; } } writeln(dp[N][0]); stdout.flush(); debug readln(); }