Go: package main

import (
        "fmt"
        "bufio"
        "os"
)

func main() {
        var n int
        var a, b string
        sc := bufio.NewScanner(os.Stdin)
        fmt.Scanf("%d", &n)
        for i := 0; i < n; i++ {
                sc.Scan()
                a = sc.Text()
                sc.Scan()
                b = sc.Text()

                if len(a) > len(b) {
                        s := add(a, b)
                        if s[len(a)] > 0 {
                                if len(a) >= 80 {
                                        fmt.Printf("overflow")
                                } else {
                                        for i := 0; i <= len(a);i++ {
                                                fmt.Printf("%d", s[len(a)-i])
                                        }
                                }
                                fmt.Printf("\n")
                        } else {
                                if len(a)-1 >= 80 {
                                        fmt.Printf("overflow")
                                } else {
                                        for i := 0; i < len(a);i++ {
                                                fmt.Printf("%d", s[len(a)-i-1])
                                        }
                                }
                                fmt.Printf("\n")
                        }
                } else {
                        s := add(b, a)
                        if s[len(b)] > 0 {
                                if len(b) >= 80 {
                                        fmt.Printf("overflow")
                                } else {
                                        for i := 0; i <= len(b);i++ {
                                                fmt.Printf("%d", s[len(b)-i])
                                        }
                                }
                                fmt.Printf("\n")
                        } else {
                                if len(b)-1 >= 80 {
                                        fmt.Printf("overflow")
                                } else {
                                        for i := 0; i < len(b);i++ {
                                                fmt.Printf("%d", s[len(b)-i-1])
                                        }
                                }
                                fmt.Printf("\n")
                        }
                }
        }
}

// expects ln > lm
func add(n string, m string) (s [100]int) {
        ln := len(n)
        lm := len(m)
        var sum [100]int

        for i := 0; i < ln; i++ {
                var s, t int
                s = int(n[ln-1-i]) - int('0')

                if lm - 1 - i >= 0 {
                        t = int(m[lm-1-i]) - int('0')
                } else {
                        t = 0
                }

                sum[i+1] = (s + t + sum[i]) / 10
                sum[i] = (s + t + sum[i]) % 10
        }

        return sum
}

Python: n = int(input())
for _ in range(n):
    a, b = input(), input()
    m = abs(len(a) - len(b))
    if len(a) > len(b):
        a = '0' + a
        b = '0' * (m+1) + b
    else:
        a = '0' * m + a
        b = '0' + b
    a, b = a[::-1], b[::-1]
    
    budget = []
    flag = False
    for i in range(0, len(a), 10):
        t = int(a[i:i+10][::-1]) + int(b[i:i+10][::-1]) 
        if flag: t += 1
        t = str(t)

        if len(t) > 10:
            t = t[1:]
            flag = True
        elif i + 10 < len(a):
            t = '0' * abs(len(t) - 10) + t
            flag = False
        else:
            flag = False
        budget.append(t)
    
    budget = ''.join(budget[::-1])
    if len(budget) < 80:
        print(budget)
    else:
        print('overflow')

Python: # python template for atcoder1
import sys
sys.setrecursionlimit(10**9)
input = sys.stdin.readline

n = int(input())
ans = []
for _ in range(n):
    a = int(input())
    b = int(input())
    s = a+b
    if s >= 10**79:
        ans.append("overflow")
    else:
        ans.append(str(s))
print("\n".join(ans))

Python: import math

n = int(input());

for i in range(n):
    
    num1 = int(input());
    num2 = int(input());
    total = num1 + num2;

    if len(str(total)) > 80:
        print("overflow");
    else:
        print(total);

Python: n=int(input())
for n in range(n):
	a=int(input())
	b=int(input())
	c=a+b
	if c>=int(1e80):
		print("overflow")
	else:
		print(c)

Python: n = input()
for i in range(n):
    a = input()
    b = input()
    c = str(a + b)
    if(len(c) >= 80):
        print("overflow")
    else:
        print(c)

Python: N=int(input())
A=[]
B=[]
for i in range(N):
    a = int(input())
    b = int(input())
    A.append(a)
    B.append(b)

for i in range(N):
    if A[i] >= 10 ** 79 or B[i] >= 10 ** 79:
        print("overflow")
    elif A[i] + B[i]>= 10 ** 79:
        print("overflow")
    else:
        print(str(A[i]+B[i]))

Python: 
if __name__ == '__main__':
    n = (int)(input())
    for _ in range(n):
        sNumber = (int)(input())
        tNumber = (int)(input())
        uNumber = sNumber+tNumber
        print("over flow" if uNumber > 10**80 else uNumber)

Python: for _ in range(int(input())):
    a=int(input())+int(input())
    print(['overflow',a][a<10**80])

Python: from math import log10
n = int(input())
for i in range(n):
    a = int(input())
    b = int(input())
    c = a+b
    if (log10(c) > 80):
        print("overflow")
    else:
        print(c)

Python: import math
n=int(input())
for i in range(n):
    fint=int(input())
    sint=int(input())
    sum=fint+sint
    if(sum<pow(10,80)):
        print (sum)
    else:
        print("overflow")

Python: l = int(input())
for i in range(l):
    a = int(input()) + int(input())
    if(a >= 1E80):
        print('overflow')
    else:
        print(a)

Python: import sys
import itertools

dataset_num = int(input())

class Overflow(Exception):
    pass

for _ in range(dataset_num):
    try:
        k1 = input()
        k2 = input()
        k1_val = [0] * 80
        k2_val = [0] * 80

        if len(k1) >= 80 or len(k2) >= 80:
            raise Overflow()
        
        for i, x in enumerate(reversed(k1)):
            k1_val[i] = int(x)

        for i, x in enumerate(reversed(k2)):
            k2_val[i] = int(x)
        
        res = [0] * 80
        for i in range(0, 80):
            res[i] += k1_val[i] + k2_val[i]
            if res[i] >= 10:
                res[i+1] += 1
                res[i] -= 10
        sumstr = "".join([str(x) for x in itertools.dropwhile(lambda x: x == 0, reversed(res))])
        if len(sumstr) >= 80:
            raise Overflow()

        print(sumstr)
    except Overflow:
        print("overflow")

Python: for i in range(int(input())):
    x = int(input())
    y = int(input())
    res = x + y
    if len(str(res)) > 80:
        print("overflow")
    else:
        print(res)

Python: n = int(input())

for i in range(n):
  a = int(input())
  b = int(input())
  s = a+b

  if len(str(s)) > 80:
    print("overflow")
  else:
    print(s)

Python: # ?????¶??????????±???????????????°??????
import sys

def main():
    n = int(sys.stdin.readline().strip())

    for _ in range(n):
        x = int(sys.stdin.readline().strip())
        y = int(sys.stdin.readline().strip())
        print(x + y)

if __name__ == '__main__':
    main()

Python: n = int(input())
for i in range(n):
  a = int(input())
  b = int(input())
  res = a + b
  if res >= 10**80:
    print("overflow")
  else :
    print (res)

Python: n = int(input())
for i in range(n):
    x = int(input())
    y = int(input())
    if x + y >= 10 ** 80:
        print("overflow")
    else:
        print(x + y)

Python: import math
n = int(input())
for i in range(n):
    x = int(input())
    y = int(input())
    if int(math.log10(x + y) + 1) > 80:
        print("overflow")
    else:
        print(x + y)