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: while 1:
    try:
        n = int(input())
    except:break

    n1 = 0
    n2 = 0
    for i in range(n):
        n1 = int(input())
        n2 = int(input())
        isOver = False
        ans = n1 + n2
        if len(str(ans)) >= 81 | len(str(n1)) | len(str(n1)) :
            isOver = True
        if isOver:
            print("overflow")
        else:
            print(ans)

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

Python: n = int(input())

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

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

c  = input();

for var in range(0, int(c)) :
	n1 = input();
	n2 = input();
	sum = int(n1) + int(n2);

	if int(math.log10(sum)) + 1 > 80 :
		print("overflow");
	else :
		print(sum);

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

Python: n = int(raw_input())
for _ in [0]*n:
  a = int(raw_input())
  b = int(raw_input())
  c = a+b
  print [c,"overflow"][len(str(c))>80]

Python: for i in range(int(input())):
    a = sum([int(j) for j in input().split()])
    if a > 2147483647:
        print("overflow")
    else:
        print(a)

Python: import sys

n = int(input())
for _ in range(n):
    a = sys.stdin.readline()
    b = sys.stdin.readline()
    c = int(a) + int(b)
    if len(str(c)) > 80:
        print("overflow")
    else:
        print(c)

Python: n=input()
for i in xrange(n):
    a=0
    for j in xrange(2):
        a+=input()
    if len(str(a))>80:
        print('overflow')
    else:
        print(a)

Python: [print((lambda x:x if x<10**80 else "overflow")(int(input())+int(input()))) for i in range(int(input()))]

Python: N = int(input())
for _ in range(N):
    f, s = [int(input()) for _ in range(2)]
    print(f+s if len(str(f+s)) <= 80 else "overflow")

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

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

Python: #!/usr/bin/env python3
# -*- coding: utf-8 -*-

# Copyright  : @Huki_Hara
# Created    : 2015-03-05

n=int(input())

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

Python: [print(i) if len(i)<=80 else print("overflow") for i in map(str,[sum([int(input()) for j in range(2)]) for i in range(int(input()))])]

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

Python: N = int(input())
import re
for _ in [0]*N:
    a = input().zfill(100)
    b = input().zfill(100)
    result = []
    prev = 0
    for i in range(1, 81):
        n = int(a[-i]) + int(b[-i]) + prev
        result.append(n%10)
        prev = n // 10
    if prev > 0 or int(a[:21]) + int(b[:21]) > 0:
        print("overflow")
    else:
        result = "".join(map(str, result[::-1]))
        print(int(result))

Python: import sys

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

Python: import math

n = int(input())
for i in range(n):
    for i in range(2):
        x = int(input())
        y = int(input())
        result = x + y
        print(result) if math.log10(result) + 1 < 10 ** 80 else print("overflow")

Python: n=int(input())

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

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

Python: for _ in range(int(input())):
    a = int(input()) + int(input())
    print(a if len(str(a)) < 81 else "overflow")

Python: #!/bin/python

def largeBudget(a, b):
  if a+b > 10e+80:
    print("overflow")
  else:
    print("%d"%(a+b))

N = int(input())
for i in range(N):
  a = int(input())
  b = int(input())
  largeBudget(a, b)

Python: n = int(input())
for i in range(0, n) :
  a, b = list(map(int, input().split()))
  sum = a + b
  if str(sum).length() > 80 :
    print("overflow")
  else :
    print(sum)