687 B | 687 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from datetime import datetime, timedelta
BLANK = " "
# inp = input
inp = lambda : sys.stdin.readline()[:-1].strip()
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():
m, n = mii()
l = [mii() for _ in range(n)]
for i in range(m):
for j in range(1, n):
l[0][i] *= l[j][i]
mx = max(l[0])
for i in range(m - 1, -1, -1):
if l[0][i] == mx:
p(i + 1)
break
if __name__ == "__main__":
tc = ii()
for t in range(1, tc+1):
ret = solve()