770 B | 770 chars
import sys
from math import sqrt, pi, sin, factorial
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = " " : [*map(int,inp().split(x))]
mfi = lambda x = " " : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
D, C, R = mii()
ans = 0
bad = [ii() for _ in range(C)]
good = [ii() for _ in range(R)]
i = 0
j = 0
while i < C and j < R:
if bad[i] <= D:
D -= bad[i]
i += 1
ans += 1
else:
D += good[j]
j += 1
ans += 1
while i < C and bad[i] <= D:
D -= bad[i]
i += 1
ans += 1
while j < R:
j += 1
ans += 1
print(ans)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
solve()