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())

list = []
for n in range(0, N):
    tmp = []
    for _ in range(0, 2):
        tmp.append(int(input()))
    list.append(tmp)

for a, b in list:
    c = a + b
    if c >= 10 ** 80:
        print('overflow')
    else:
        print(str(c))

Python: while True:
    n = int(input())
    for _ in range(n):
        a, b = int(input()), int(input())
        x = str(a+b)
        print('overflow' if len(x) > 80 else x)

Python: n = int(input())

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

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

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

Python: N=int(input())
a=[None]*N
b=[None]*N
for i in range(0,N):
  a[i]=int(input())
  b[i]=int(input())
for i in range(0,N):
  if len(str(a[i]))>80:
    print("overflow")
  elif len(str(b[i]))>80:
    print("overflow")
  elif len(str(a[i]+b[i]))>80:
    print("overflow")
  else:
    print(a[i]+b[i])

Python: n=int(input())
for n in range(n):
	a=int(input())
	b=int(input())
	c=a+b
	if c>=int(1e79):
		print("overflow")
	else:
		print(c)

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

Python: for i in range(int(input())):
  ans = int(input()) + int(input())
  print(ans if len(str(ans)) <= 80 else "overflow")

Python: n = int(input())

for i in range(0, n):
    a = int(input())
    b = int(input())
    if len(str(a + b)) > 80:
        print("overflow")
    elif len(str(a)) > 80:
        print("overflow")
    elif len(str(b)) > 80:
        print("overflow")
    else :
        print(a + b)

Python: # -*- coding: utf-8 -*-
N = int(input())

for _ in range(N):
    a = int(input())
    b = int(input())
    s = str(a + b)
    if len(s) <= 80:
        print(s)
    else:
        print('overflow')

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

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

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

        if len(x) > 80 or len(y) > 80:
            print('overflow')
        else:
            ans = int(x) + int(y)
            if len(str(ans)) > 80:
                print('overflow')
            else:
                print(ans)

if __name__ == '__main__':
    main()

Python: #!/usr/bin/env python
#-*- coding:utf-8 -*-

import sys
import math

def digit(x):
    d = 0
    while x >= 1:
        x /= 10
        d += 1

    return d

n = int(input())
anss = []

for _ in range(n):
    x = int(input())
    y = int(input())
    if int(digit(x)) > 80:
        print("overflow")
    elif int(digit(y)) > 80:
        print("overflow")
    elif int(digit(x+y)) > 80:
        print("overflow")
    else:
        anss.append(x+y)

for data in anss:
    print(data)

Python: # -*- coding:utf-8 -*-

def main():
    LIST=[]
    for i in range(int(input())):
        a=int(input())
        b=int(input())
        LIST.append(a+b)

        if len(LIST)>80:
            print("overflow")
            break

    for v in LIST:
        print(str(v))
            
    
if __name__ == '__main__':
    main()

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

Python: def main():
    n = int(input())

    for i in range(n):
        result = str(int(input()) + int(input()))

        if len(result) > 80:
            print("overflow")
        else:
            print(result)

if __name__ == '__main__':
    main()

Python: from sys import stdin
n = int(stdin.readline())
for i in range(n):
    c = str(int(stdin.readline().strip()) + int(stdin.readline().strip()))
    if (len(c) > 80):
        print("overflow")
    else:
        print(c)

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

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

Python: n=int(input())
for _ in range(n):
	s=int(input())+int(input())
	print('overflow' if s/1e80>1 else s)

Python: n=int(input())
ans_list=[]

for i in range(n):
	a=int(input())
	b=int(input())
	ans_list.append(a+b)

for i in ans_list:
	print(i)