import os import sys from io import BytesIO, IOBase BUFSIZE = 8192 class FastIO(IOBase): newlines = 0 def __init__(self, file): self._fd = file.fileno() self.buffer = BytesIO() self.writable = "x" in file.mode or "r" not in file.mode self.write = self.buffer.write if self.writable else None def read(self): while True: b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE)) if not b: break ptr = self.buffer.tell() self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr) self.newlines = 0 return self.buffer.read() def readline(self): while self.newlines == 0: b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE)) self.newlines = b.count(b"\n")+(not b) ptr = self.buffer.tell() self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr) self.newlines -= 1 return self.buffer.readline() def flush(self): if self.writable: os.write(self._fd, self.buffer.getvalue()) self.buffer.truncate(0), self.buffer.seek(0) class IOWrapper(IOBase): def __init__(self, file): self.buffer = FastIO(file) self.flush = self.buffer.flush self.writable = self.buffer.writable self.write = lambda s:self.buffer.write(s.encode("ascii")) self.read = lambda:self.buffer.read().decode("ascii") self.readline = lambda:self.buffer.readline().decode("ascii") sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout) input = lambda:sys.stdin.readline().rstrip("\r\n") mod = 998244353 h,w,k = map(int,input().split()) ans = 0 for i in range(k): x,y,v = map(int,input().split()) #print(x-w-1+y, x-y) ans += x * x % mod * v ans %= mod if x-w-1+y > 0: ans -= max(0, (x-w-1+y) * (x-w+y) // 2) * v ans %= mod if x-y > 0: ans -= max(0, (x-y) * (x-y+1) // 2) * v ans %= mod #print(ans) print(ans)