Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline


N = int(input())
A = ["?"]*N


def f2(i):
    global A
    s = A[i]
    if s == "?":
        print(i, flush=True)
        s = input().strip()
        A[i] = s
    if s == "Vacant":
        exit()
    return s


def f(l, r):
    m = (l+r)//2
    f2(m)

    if ((m-l) % 2 and A[l] == A[m]) or ((m-l) % 2 == 0 and A[l] != A[m]):
        f(l, m-1)
    elif ((r-m) % 2 and A[m] == A[r]) or ((r-m) % 2 == 0 and A[m] != A[r]):
        f(m+1, r)


def main():
    f2(0)
    f2(N-1)
    f(0, N-1)


if __name__ == '__main__':
    main()


Fixed submission:
import sys
input = sys.stdin.readline


def q(i):
    print(i, flush=True)
    s = input().strip()
    if s == "Vacant":
        exit()
    return s


def f(l, r, lc, rc):
    m = (l+r)//2
    mc = q(m)

    if ((m-l) % 2 and lc == mc) or ((m-l) % 2 == 0 and lc != mc):
        f(l, m, lc, mc)
    elif ((r-m) % 2 and mc == rc) or ((r-m) % 2 == 0 and mc != rc):
        f(m, r, mc, rc)


def main():
    N = int(input())
    lc = q(0)
    rc = q(N-1)
    f(0, N-1, lc, rc)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline


def main():
    N = int(input())
    A = ["?"]*N

    l, x, r = 0, N//2, N-1
    while True:
        ls = A[l]
        if ls == "?":
            print(l, flush=True)
            ls = input().strip()
            if ls == "Vacant":
                return
            A[l] = ls

        xs = A[x]
        if xs == "?":
            print(x, flush=True)
            xs = input().strip()
            if xs == "Vacant":
                return
            A[x] = xs

        rs = A[r]
        if rs == "?":
            print(r, flush=True)
            rs = input().strip()
            if rs == "Vacant":
                return
            A[r] = rs

        if ls != xs:
            if (x-l) % 2:
                l, x, r = x, (x+r)//2, r
            else:
                l, x, r = l, (l+x)//2, x
        elif rs != xs:
            if (r-x) % 2:
                l, x, r = l, (l+x)//2, x
            else:
                l, x, r = x, (x+r)//2, r
        else:
            l, x, r = x, (x+r)//2, r


if __name__ == '__main__':
    main()


Fixed submission:
import sys
input = sys.stdin.readline


def q(i):
    print(i, flush=True)
    s = input().strip()
    if s == "Vacant":
        exit()
    return s


def f(l, r, lc, rc):
    m = (l+r)//2
    mc = q(m)

    if ((m-l) % 2 and lc == mc) or ((m-l) % 2 == 0 and lc != mc):
        f(l, m, lc, mc)
    elif ((r-m) % 2 and mc == rc) or ((r-m) % 2 == 0 and mc != rc):
        f(m, r, mc, rc)


def main():
    N = int(input())
    lc = q(0)
    rc = q(N-1)
    f(0, N-1, lc, rc)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline


def main():
    N = int(input())
    A = ["?"]*N

    l, x, r = 0, N//2, N-1
    while True:
        ls = A[l]
        if ls == "?":
            print(l, flush=True)
            ls = input().strip()
            if ls == "Vacant":
                return
            A[l] = ls

        xs = A[x]
        if xs == "?":
            print(x, flush=True)
            xs = input().strip()
            if xs == "Vacant":
                return
            A[x] = xs

        rs = A[r]
        if rs == "?":
            print(r, flush=True)
            rs = input().strip()
            if rs == "Vacant":
                return
            A[r] = rs

        if ls != xs:
            l, x, r = l, (l+x)//2, x
        elif rs != xs:
            l, x, r = x, (x+r)//2, r


if __name__ == '__main__':
    main()


Fixed submission:
import sys
input = sys.stdin.readline


def q(i):
    print(i, flush=True)
    s = input().strip()
    if s == "Vacant":
        exit()
    return s


def f(l, r, lc, rc):
    m = (l+r)//2
    mc = q(m)

    if ((m-l) % 2 and lc == mc) or ((m-l) % 2 == 0 and lc != mc):
        f(l, m, lc, mc)
    elif ((r-m) % 2 and mc == rc) or ((r-m) % 2 == 0 and mc != rc):
        f(m, r, mc, rc)


def main():
    N = int(input())
    lc = q(0)
    rc = q(N-1)
    f(0, N-1, lc, rc)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline


def main():
    N = int(input())
    A = ["?"]*N

    l, x, r = 0, N//2, N-1
    while True:
        ls = A[l]
        if ls == "?":
            print(l)
            ls = input().strip()
            if ls == "Vacant":
                return
            A[l] = ls

        xs = A[x]
        if xs == "?":
            print(x)
            xs = input().strip()
            if xs == "Vacant":
                return
            A[x] = xs

        rs = A[r]
        if rs == "?":
            print(r)
            rs = input().strip()
            if rs == "Vacant":
                return
            A[r] = rs

        if ls != xs:
            l, x, r = l, (l+x)//2, x
        elif rs != xs:
            l, x, r = x, (x+r)//2, r


if __name__ == '__main__':
    main()


Fixed submission:
import sys
input = sys.stdin.readline


def q(i):
    print(i, flush=True)
    s = input().strip()
    if s == "Vacant":
        exit()
    return s


def f(l, r, lc, rc):
    m = (l+r)//2
    mc = q(m)

    if ((m-l) % 2 and lc == mc) or ((m-l) % 2 == 0 and lc != mc):
        f(l, m, lc, mc)
    elif ((r-m) % 2 and mc == rc) or ((r-m) % 2 == 0 and mc != rc):
        f(m, r, mc, rc)


def main():
    N = int(input())
    lc = q(0)
    rc = q(N-1)
    f(0, N-1, lc, rc)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline


def main():
    N = int(input())
    A = ["?"]*N

    l, x, r = 0, N//2, N-1
    while True:
        ls = A[l]
        if ls == "?":
            print(l)
            ls = input().strip()
            A[l] = ls

        xs = A[x]
        if xs == "?":
            print(x)
            xs = input().strip()
            A[x] = xs

        rs = A[r]
        if rs == "?":
            print(r)
            rs = input().strip()
            A[r] = rs

        if ls != xs:
            l, x, r = l, (l+x)//2, x
        elif rs != xs:
            l, x, r = x, (x+r)//2, r


if __name__ == '__main__':
    main()


Fixed submission:
import sys
input = sys.stdin.readline


def q(i):
    print(i, flush=True)
    s = input().strip()
    if s == "Vacant":
        exit()
    return s


def f(l, r, lc, rc):
    m = (l+r)//2
    mc = q(m)

    if ((m-l) % 2 and lc == mc) or ((m-l) % 2 == 0 and lc != mc):
        f(l, m, lc, mc)
    elif ((r-m) % 2 and mc == rc) or ((r-m) % 2 == 0 and mc != rc):
        f(m, r, mc, rc)


def main():
    N = int(input())
    lc = q(0)
    rc = q(N-1)
    f(0, N-1, lc, rc)


if __name__ == '__main__':
    main()