#include <cstdio>
#define rep(i, d, u) for(int i = d; i <= u; ++i)
#define dep(i, u, d) for(int i = u; i >= d; --i)
int ured() {
	int re = 0;
	char ch;
	do {
		ch = getchar();
	} while('9' < ch || ch < '0');
	do {
		re = re * 10 + (ch ^ '0');
	} while('0' <= (ch = getchar()) && ch <= '9');
	return re;
}
int ired() {
	int re = 0;
	char ch;
	bool st = 0;
	do {
		ch = getchar();
	} while(('9' < ch || ch < '0') && ch != '-');
	if(ch == '-') {
		ch = getchar(), st = 1;
	}
	do {
		re = re * 10 + (ch ^ '0');
	} while('0' <= (ch = getchar()) && ch <= '9');
	return st ? -re : re;
}
void uwit(int da) {
	int ch[21], cn = 0;
	do {
		ch[++cn] = da - da / 10 * 10;
	} while(da /= 10);
	do {
		putchar('0' ^ ch[cn]);
	} while(--cn);
}
int min(int le, int ri) {
	return le < ri ? le : ri;
}
void swap(int &le, int &ri) {
	int tp = le;
	le = ri, ri = tp;
}
const int _maxn = 400011, _maxb = 31, _mods = 998244353;
int qpow(int da, int up) {
	int re = 1;
	while(up) {
		if(up & 1) {
			re = 1ll * re * da % _mods;
		}
		da = 1ll * da * da % _mods, up >>= 1;
	}
	return re;
}
void ince(int &le, int ri) {
	if((le += ri) >= _mods) {
		le -= _mods;
	}
}
int incd(int le, int ri) {
	return le + ri >= _mods ? le + ri - _mods : le + ri;
}
int decd(int le, int ri) {
	return le - ri < 0 ? le - ri + _mods : le - ri;
}
int gpow[31], ginv[31], gpod[_maxn << 3], gind[_maxn << 3], lens, into[_maxn << 2];
void yclg() {
	gpow[23] = 15311432, ginv[23] = 469870224;
	dep(i, 22, 0) {
		gpow[i] = 1ll * gpow[i + 1] * gpow[i + 1] % _mods, ginv[i] = 1ll * ginv[i + 1] * ginv[i + 1] % _mods;
	}
}
void fini(int cn) {
	for(lens = 1; lens < cn; lens <<= 1);
	for(int i = 1, j = 1; i < lens; i <<= 1, ++j) {
		if(!gpod[i]) {
			gpod[i] = gind[i] = 1;
			rep(k, i + 1, (i << 1) - 1) {
				gpod[k] = 1ll * gpod[k - 1] * gpow[j] % _mods, gind[k] = 1ll * gind[k - 1] * ginv[j] % _mods;
			}
		}
	}
	rep(i, 1, lens - 2) {
		into[i] = into[i >> 1] >> 1 | (i & 1 ? lens >> 1 : 0);
	}
}
void fntt(int *fr, bool st) {
	rep(i, 1, lens - 2) {
		if(i < into[i]) {
			swap(fr[i], fr[into[i]]);
		}
	}
	int rg, *po;
	for(int i = 1, j = 1; i < lens; i <<= 1, ++j) {
		for(int k = 0; k < lens; k += i << 1) {
			po = (st ? gpod + i : gind + i);
			rep(l, k, k + i - 1) {
				fr[l + i] = decd(fr[l], rg = 1ll * fr[l + i] * *po++ % _mods), ince(fr[l], rg);
			}
		}
	}
	if(!st) {
		rg = qpow(lens, _mods - 2);
		rep(i, 0, lens - 1) {
			fr[i] = 1ll * fr[i] * rg % _mods;
		}
	}
}
void fcpy(int *fr, int *re, int ln) {
	rep(i, 0, ln - 1) {
		re[i] = fr[i];
	}
}
void fclr(int *re, int ln) {
	rep(i, 0, ln - 1) {
		re[i] = 0;
	}
}
void ftim(int *le, int *ri, int *re) {
	rep(i, 0, lens - 1) {
		re[i] = 1ll * le[i] * ri[i] % _mods;
	}
}
int cpyl[_maxn << 2], cpyr[_maxn << 2];
void fcal(int *le, int *ri, int *re, int ln, int rn, int en) {
	fini(ln + rn - 1), fcpy(le, cpyl, ln), fclr(cpyl + ln, lens - ln), fcpy(ri, cpyr, rn), fclr(cpyr + rn, lens - rn);
	fntt(cpyl, 1), fntt(cpyr, 1), ftim(cpyl, cpyr, cpyl), fntt(cpyl, 0), fcpy(cpyl, re, en);
}
int cpya[_maxn << 2], cpyb[_maxn << 2];
void finv(int *fr, int *re, int ln) {
	int ri;
	re[0] = qpow(fr[0], _mods - 2);
	for(int i = 1; i < ln; i <<= 1) {
		fini(i << 1), ri = min(i << 1, ln);
		fcpy(fr, cpya, ri), fclr(cpya + ri, lens - ri), fcpy(re, cpyb, i), fclr(cpyb + i, lens - i);
		fntt(cpya, 1), fntt(cpyb, 1), ftim(cpya, cpyb, cpya), fntt(cpya, 0), fclr(cpya, i);
		fntt(cpya, 1), ftim(cpya, cpyb, cpya), fntt(cpya, 0);
		rep(j, i, ri - 1) {
			re[j] = _mods - cpya[j];
		}
	}
}
int ycln[_maxn << 2], cpyc[_maxn << 2], cpyd[_maxn << 2];
void fcdq(int *re, int le, int ri) {
	if(le + 1 == ri) {
		if(le) {
			re[le] = 1ll * re[le] * ycln[le] % _mods;
		} else {
			re[le] = 1;
		}
	} else {
		fcdq(re, le, le + ri >> 1), fcal(cpyc, re + le, cpyd, ri - le, (ri + le >> 1) - le, ri - le);
		rep(i, le + ri >> 1, ri - 1) {
			ince(re[i], cpyd[i - le]);
		}
		fcdq(re, le + ri >> 1, ri);
	}
}
void fexp(int *fr, int *re, int ln) {
	rep(i, 0, ln - 1) {
		cpyc[i] = 1ll * i * fr[i] % _mods, re[i] = 0;
	}
	fcdq(re, 0, ln);
}
void fder(int *re, int ln) {
	rep(i, 0, ln - 2) {
		re[i] = 1ll * (i + 1) * re[i + 1] % _mods;
	}
	re[ln - 1] = 0;
}
void fint(int *re, int ln) {
	dep(i, ln - 1, 1) {
		re[i] = 1ll * ycln[i] * re[i - 1] % _mods;
	}
	re[0] = 0;
}
int cpyf[_maxn << 2], cpyg[_maxn << 2];
void fqln(int *fr, int *re, int ln) {
	fcpy(fr, cpyf, ln), fder(cpyf, ln), finv(fr, cpyg, ln), fcal(cpyf, cpyg, re, ln - 1, ln, ln), fint(re, ln);
}
int cpyh[_maxn << 2];
void fpow(int *fr, int *re, int up, int ln) {
	fqln(fr, cpyh, ln);
	rep(i, 0, ln - 1) {
		cpyh[i] = 1ll * cpyh[i] * up % _mods;
	}
	fexp(cpyh, re, ln);
}

int abs(int da) {
	return da < 0 ? -da : da;
}
int xf, xs, xt, n, datf[_maxn], dats[_maxn];
int solv(int da) {
	int re = 0;
	rep(i, 0, n << 1) {
		re = (1ll * abs(n - da - i) * dats[i] + re) % _mods;
	}
	return 1ll * re * qpow(3, _mods - n - 1) % _mods;
}
int main() {
	xf = ired(), xs = ired(), xt = ired(), n = ured(), yclg(), ycln[1] = 1;
	rep(i, 2, n << 1) {
		ycln[i] = _mods - 1ll * _mods / i * ycln[_mods % i] % _mods;
	}
	datf[0] = datf[1] = datf[2] = 1, fpow(datf, dats, n, n << 1 | 1);
	uwit((0ll + solv(abs(xf - xs)) + solv(abs(xf - xt)) + solv(abs(xs - xt))) * (_mods + 1 >> 1) % _mods), putchar('\n');
	return 0;
}