Buggy python submission (verdict: Time Limit Exceeded):
import bisect
import sys
import math
from collections import deque
from heapq import heappush, heappop

def sRaw():
    return input().rstrip("\r")


def iRaw():
    return int(input())


def ssRaw():
    return input().split()


def isRaw():
    return list(map(int, ssRaw()))


INF = 1 << 29

#DIV = (10**9) + 7
DIV = 998244353

def mod_inv_prime(a, mod=DIV):
    return pow(a, mod-2, mod)


def mod_inv(a, b):
    r = a
    w = b
    u = 1
    v = 0
    while w != 0:
        t = r//w
        r -= t*w
        r, w = w, r
        u -= t*v
        u, v = v, u
    return (u % b+b) % b


def CONV_TBL(max, mod=DIV):
    fac, finv, inv = [0]*max, [0]*max, [0]*max
    fac[0] = fac[1] = 1
    finv[0] = finv[1] = 1
    inv[1] = 1
    for i in range(2, max):
        fac[i] = fac[i-1]*i % mod
        inv[i] = mod - inv[mod % i] * (mod//i) % mod
        finv[i] = finv[i-1]*inv[i] % mod

    class CONV:
        def __init__(self):
            self.fac = fac
            self.finv = finv
            pass

        def ncr(self, n, k):
            if(n < k):
                return 0
            if(n < 0 or k < 0):
                return 0
            return fac[n]*(finv[k]*finv[n-k] % DIV) % DIV

    return CONV()


def cumsum(As):
    s = 0
    for a in As:
        s += a
        yield s


sys.setrecursionlimit(200005)


def dijkstra(G,start=0):
    heap = []
    cost = [INF]*len(G)
    heappush(heap,(0,start))
    while len(heap)!=0:
        c,n = heappop(heap)
        if cost[n] !=INF:
            continue
        cost[n]=c
        for e in G[n]:
            ec,v = e
            if cost[v]!=INF:
                continue
            heappush(heap,(ec+c,v))
    return cost


def main():
    N,M,K = isRaw()
    As = isRaw()
    Bs = isRaw()
    sAs = [0]
    for a in As:
        t = a + sAs[-1]
        if t>K:
            break
        sAs.append(t)

    sBs=[0]
    for b in Bs:
        t = b + sBs[-1]
        if t>K:
            break
        sBs.append(t)

    ai = len(sAs)-1
    bi = len(sBs)-1
    while sAs[ai]+sBs[bi] > K:
        if ai==0 and bi==0:
            break
        dA = 10**9+1
        if ai!=0:
            dA = sAs[ai]-sAs[ai-1]
        dB = 10**9+1
        if bi!=0:
            dB = sBs[bi]-sBs[bi-1]
        if dA >dB:
            ai=ai-1
            if bi+1!=len(sBs) and sAs[ai]+sBs[bi+1]<=sAs[ai+1]+sBs[bi]:
                bi+=1
        else:
            bi=bi-1
            if ai+1 != len(sAs) and sAs[ai+1]+sBs[bi] <= sAs[ai]+sBs[bi+1]:
                ai += 1
    print(ai+bi)


main()


Fixed submission:
import bisect
import sys
import math
from collections import deque
from heapq import heappush, heappop

def sRaw():
    return input().rstrip("\r")


def iRaw():
    return int(input())


def ssRaw():
    return input().split()


def isRaw():
    return list(map(int, ssRaw()))


INF = 1 << 29

#DIV = (10**9) + 7
DIV = 998244353

def mod_inv_prime(a, mod=DIV):
    return pow(a, mod-2, mod)


def mod_inv(a, b):
    r = a
    w = b
    u = 1
    v = 0
    while w != 0:
        t = r//w
        r -= t*w
        r, w = w, r
        u -= t*v
        u, v = v, u
    return (u % b+b) % b


def CONV_TBL(max, mod=DIV):
    fac, finv, inv = [0]*max, [0]*max, [0]*max
    fac[0] = fac[1] = 1
    finv[0] = finv[1] = 1
    inv[1] = 1
    for i in range(2, max):
        fac[i] = fac[i-1]*i % mod
        inv[i] = mod - inv[mod % i] * (mod//i) % mod
        finv[i] = finv[i-1]*inv[i] % mod

    class CONV:
        def __init__(self):
            self.fac = fac
            self.finv = finv
            pass

        def ncr(self, n, k):
            if(n < k):
                return 0
            if(n < 0 or k < 0):
                return 0
            return fac[n]*(finv[k]*finv[n-k] % DIV) % DIV

    return CONV()


def cumsum(As):
    s = 0
    for a in As:
        s += a
        yield s


sys.setrecursionlimit(200005)


def dijkstra(G,start=0):
    heap = []
    cost = [INF]*len(G)
    heappush(heap,(0,start))
    while len(heap)!=0:
        c,n = heappop(heap)
        if cost[n] !=INF:
            continue
        cost[n]=c
        for e in G[n]:
            ec,v = e
            if cost[v]!=INF:
                continue
            heappush(heap,(ec+c,v))
    return cost


def main():
    N,M,K = isRaw()
    As = isRaw()
    Bs = isRaw()
    sAs = [0]
    for a in As:
        t = a + sAs[-1]
        if t>K:
            break
        sAs.append(t)

    sBs=[0]
    for b in Bs:
        t = b + sBs[-1]
        if t>K:
            break
        sBs.append(t)
    sBs = sBs[1:]
    ans = 0
    for sai,sa in enumerate(sAs):
        
        sbi = bisect.bisect_right(sBs,K-sa)
        ans = max(ans,sai+sbi)
    print (ans)


main()