# Đọc toàn bộ các token từ input
inp = open(0).read().split()
if inp:
    t = int(inp[0])
    ptr = 1
 
    for _ in range(t):
        n = int(inp[ptr])
        ptr += 1
 
        has = set()
        total = 0
        ans = 0
 
        # Đọc n cặp số (x, y)
        for _ in range(n):
            x = int(inp[ptr])
            y = int(inp[ptr+1])
            ptr += 2
            has.add(x)
            total += y
            if x > ans:
                ans = x
 
        # Tính toán kết quả MEX tối đa
        cost = 0
        v = 0
        while True:
            c = 1 if (v in has or v == 0) else (1 << (v - 1))
            cost += c
 
            if cost <= total:
                if v + 1 > ans:
                    ans = v + 1
                v += 1
            else:
                break
 
        print(ans)
 

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10
4
2 2
0 3
4 1
1 2
1
10 1
1
2 3
3
0 1
2 2
3 1
3
0 4
1 2
2 1
1
0 100
2
2 7
3 1
2
0 1
3 3
3
0 1
1 1
59 1
4
0 5
1 1
2 3
3 1