from __future__ import division, print_function

import math
import os
import sys
from __builtin__ import xrange as range
from cStringIO import StringIO
from future_builtins import ascii, filter, hex, map, oct, zip
from io import IOBase

import __pypy__

#  =========     /\       /|    |====/|
#      |        /  \       |    |   / |
#      |       /____\      |    |  /  |
#      |      /      \     |    | /   |
#  ========= /        \  =====  |/====|  
#  code
def cool(mid,n,m):
    k = ((n + 1) * n) // 2 - mid
    if k >= n - m:
        return True
    else:
        return False
def main():
    t = int(input())
    for _ in range(t):
        n,m = map(int , input().split())
        if m == 0:
            print(0)
            continue
        l = 0
        r = 2 * 10**18
        ans = 0
        while l <= r:
            mid = (r - l)//2 + l
            if cool(mid,n,m):
                l = mid + 1
                ans = max(ans,mid)
            else:
                r = mid - 1
        print(ans)
    return
    #end main


# region fastio

BUFSIZE = 8192


class FastI(IOBase):
    def __init__(self, file):
        self._fd = file.fileno()
        self._buffer = StringIO()
        self.newlines = 0

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count("\n") + (not b)
            ptr = self._buffer.tell()
            self._buffer.seek(0, 2), self._buffer.write(b), self._buffer.seek(ptr)
        self.newlines -= 1
        return self._buffer.readline()


class FastO(IOBase):
    def __init__(self, file):
        self._fd = file.fileno()
        self._buffer = __pypy__.builders.StringBuilder()
        self.write = lambda s: self._buffer.append(s)

    def flush(self):
        os.write(self._fd, self._buffer.build())
        self._buffer = __pypy__.builders.StringBuilder()


def print(*args, **kwargs):
    sep, file = kwargs.pop("sep", " "), kwargs.pop("file", sys.stdout)
    at_start = True
    for x in args:
        if not at_start:
            file.write(sep)
        file.write(str(x))
        at_start = False
    file.write(kwargs.pop("end", "\n"))
    if kwargs.pop("flush", False):
        file.flush()


sys.stdin, sys.stdout = FastI(sys.stdin), FastO(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")

# endregion

if __name__ == "__main__":
    main()