Template:
[code]
#include <iostream>
#include <string>
using namespace std;

int main() {
    unsigned long guess = [initial guess];
    string response;
    while (1) {
        cout << guess << endl; // endl automatically flushes in C++
        cin >> response;
        if (response == "Lower") {
            guess = [lower guess];
        } else if (response == "Higher") {
            guess = [higher guess];
        } else if (response == "OK") {
            break;
        }
    }
}
[/code]

 
#include <iostream> 
#include <string> 
using namespace std; 
 
int main() { 
    unsigned long guess = [initial guess]; 
    string response; 
    while (1) { 
        cout << guess << endl; // endl automatically flushes in C++ 
        cin >> response; 
        if (response == "Lower") { 
            guess = [lower guess]; 
        } else if (response == "Higher") { 
            guess = [higher guess]; 
        } else if (response == "OK") { 
            break; 
        } 
    } 
} 

Do you have the Phyton 3 template? I still don't really understand the flush system.

[code]
import sys
guess = #(initial guess)
response = ''
while (1):
    print (guess)
    sys.stdout.flush()
    response = input()
    if (response == "Lower"):
        guess = #(lower guess)
    elif (response == "Higher"):
        guess = #(higher guess)
    elif (response == "OK"):
        break
[/code]

 
import sys 
guess = #(initial guess) 
response = '' 
while (1): 
    print (guess) 
    sys.stdout.flush() 
    response = input() 
    if (response == "Lower"): 
        guess = #(lower guess) 
    elif (response == "Higher"): 
        guess = #(higher guess) 
    elif (response == "OK"): 
        break 

I can't see why putting guess and response outside the loop, but thanks man: I was about to give it a shot and even though I would have gone first for that road, you surely saved me some trial&error anxiety.

Too bad now it is not accepting Python 3 code :(

I'm not going to tell you what they are, but I can tell you what you output.

For test case #4, the TLE actually means that you've exceeded the allotted amount of guesses (you're taking 32 or more guesses).

For test case #5, your guess is -2147483648. (This is because when you cast it to an int32_t you get 2^32, which when converted to a signed number wraps around.)

The only thing I can tell you is you're approaching the problem incorrectly -- there's a more optimal (read: more correct) way to guess.