730 B | 708 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from datetime import datetime, timedelta
sys.setrecursionlimit(10**7)
BLANK = " "
#inp = input
inp = lambda : sys.stdin.readline().rstrip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
D, N = mii() # D: 목적지, N: 도로에 있는 말의 수
l = [mii() for _ in range(N)]
mx_t = 0
for loc, v in l:
dis = D - loc
t = dis / v
mx_t = max(mx_t, t)
return D / mx_t
if __name__ == "__main__":
tc = ii()
for t in range(1, tc+1):
ret = solve()
p(f"Case #{t}: {ret}")