Go: package main

import (
	"fmt"
	"os"
	"strconv"
	"bufio"
	"strings"
	"sort"
)

// define
var (
	sc = bufio.NewScanner(os.Stdin)
)

func bordersInt(in_map [][]int, invalid int) [][]int{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]int, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]int, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func bordersString(in_map [][]string, invalid string) [][]string{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]string, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]string, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func scanIntLine(len int) []int{
	arr := make([]int, len)
	for i:=0; i<len; i++{
		sc.Scan()
		tmp, err := strconv.Atoi(sc.Text())
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func scanStringLine(len int) []string{
	arr := make([]string, len)
	for i:=0; i<len; i++{
		sc.Scan()
		arr[i] = sc.Text()
	}
	return arr
}

func scanIntSplit(len int) []int{
	arr := make([]int, len)
	sc.Scan()
	for i, v := range strings.Split(sc.Text(), " "){
		tmp, err := strconv.Atoi(v)
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func maxInt(args... int) int{
	sort.Ints(args)
	return args[len(args)-1]
}

func main(){
	buf := make([]byte, 0)
    sc.Buffer(buf, 1000000009)
	var n int 
	fmt.Scan(&n)
	dp := make([][]int, 1003)
	for i:=0; i<1003; i++ {
		dp[i] = make([]int, 1003)
	}
	input_lines := scanStringLine(2*n)
	for i:=0; i<n; i++ {
		S, T := input_lines[2*i], input_lines[2*i+1]
		lenS, lenT := len(S), len(T)
		for i:=1; i<lenS+1; i++ {
			for j:=1; j<lenT+1; j++ {
				if S[i-1] == T[j-1] {
					dp[i][j] = maxInt(dp[i-1][j-1]+1, dp[i-1][j], dp[i][j-1])
				} else {
					dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
				}
			}
		}
		fmt.Println(dp[lenS][lenT])
	}
}

Python: # -*- coding: utf-8 -*-
"""
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_10_C

????????±?????¨??????
"""
import sys
from sys import stdin
input = stdin.readline


C = []
def calc_lcs4(X, Y):
    """
    Y[j]?????¢???????????????????????´
    ?????????????????????????????°?????????????????????????????´
    ????????±?????¨???????????¢??°?????§?¨????????????????????????´
    4/5 ?????????????????????????????¨?????????????????????????????°????????¨??????????????? 5.6?§?
    """
    global C
    X = ' ' + X
    Y = ' ' + Y
    m = len(X)
    n = len(Y)

    C = [[0]*(n+1) for _ in range(m+2)] #  ???????????§??¨???

    max_lcs = 0

    pre_row = C[0]
    for i in range(1, m):
        row = C[i]
        XX = X[i]
        for j, YY in enumerate(Y):
            if XX == YY:
                pr_j1 = pre_row[j - 1]
                row[j] = pr_j1 + 1
                if pr_j1+1 > max_lcs:
                   max_lcs = pr_j1 + 1
            else:
                pr_j = pre_row[j]
                r_j1 = row[j-1]
                if pr_j >= r_j1:
                    row[j] = pr_j
                else:
                    row[j] = r_j1
        pre_row = row

    print(max_lcs)


if __name__ == '__main__':
    num = int(input())

    for _ in range(num):
        X = input().strip()
        Y = input().strip()

        result = calc_lcs4(X, Y)

Python: def prep_array(X, Y):
    c = [[0]*1001 for _ in range(1000+1)]
    return c


def calc_lcs(X, Y, c):
    m = len(X)
    n = len(Y)
    X = ' ' + X
    Y = ' ' + Y

    pre_row = c[0]
    for i in range(1, m+1):
        row = c[i]
        for j in range(1, n+1):
            if X[i] == Y[j]:
                row[j] = pre_row[j - 1] + 1
            elif pre_row[j] >= row[j - 1]:
                row[j] = pre_row[j]
            else:
                row[j] = row[j - 1]
        pre_row = row
    return check_max(c)


def check_max(array):
    max_lcs = 0
    for row in array:
        temp_max = max(row)
        if temp_max > max_lcs:
            max_lcs = temp_max
    return max_lcs


if __name__ == '__main__':
    # ??????????????\???
    num = int(input())
    # f = open('input.txt')
    # num = int(f.readline())

    for _ in range(num):
        X = input()
        Y = input()
        # X = f.readline().strip()
        # Y = f.readline().strip()

        # ???????????????
        result = calc_lcs(X, Y, prep_array(X, Y))

        # ???????????¨???
        print(result)

Python: for _ in[0]*int(input()):
 X,Y,z=input(),input(),[]
 for y in Y:
  s=0
  for i,k in enumerate(z):
   t=X.find(y,s)+1
   if t<1:break
   if t<k:z[i]=t
   s=k
  else:
   t=X.find(y,s)+1
   if t:z+=[t]
 print(len(z))

Python: def make_lcs(lhs , rhs):
    c = [[0 for _ in range(len(rhs) + 1)] for _ in range(len(lhs) + 1)]
    for l_i in range(len(lhs)):
        for r_i in range(len(rhs)):
            if lhs[l_i] == rhs[r_i]:
                c[l_i + 1][r_i + 1] = c[l_i][r_i] + 1
            else:
                c[l_i + 1][r_i + 1] = max(c[l_i][r_i + 1], c[l_i + 1][r_i])
    print(c[-1][-1])


if __name__ == '__main__':
    n = int(input())
    for _ in range(n):
        lhs = [i for i in input().rstrip()]
        rhs = [i for i in input().rstrip()]
        make_lcs(lhs, rhs)

Python: #Longest Common Subsequence
#?????????

def lastindex(a,x):
    #????????????a??????????????????????????????x??????????????????????????????????????????1???????????????????????????x????????¨???????????¨??????-1????????????
    try:
        return len(a)-a[::-1].index(x)-2
    except:
        return(-1)

'''
X={x1,x2,...xm}
Y={y1,y2,...yn}????????????

Xi={x1,x2,...xi}(1<=i<=m)
Yj={y1,y2,...yj}(1<=j<=n)
Z(i,j)=Xi??¨Yj???????????±?????¨???????????????
??¨?????????????????¨???

Zi,j=max{
	Z(lastindex(Xi,yj),j-1)+1
	Z(i-1,lastindex(Yj,xi))+1
	Z(i-1,j)
	Z(i,j-1)
}
??¨?????????
??¢??°lastindex??§???(Zi,j????¨????????????¨????????§?????????)??????1??????????????????????????????????????????lastindex(a,x)???0?????¨??????lastindex(a,i)-1=-1??¨?????£???????????????Z[lastindex(a,x)-1][...]?????¨?????\?????????????????£?????????????????????
a?????????x????????¨???????????????????????????-1??¨???????????¨??§?????????????????°???????????§?????¨??????-1?????????????????????
'''

#????????????????????°????????§?????£???????????????AOJ????????????????????¨??????????????????X??¨Y????\???????????????¨??????TLE??¨?????£???????????£??????

q=int(input())


for repeat in range(q):
    X=input()
    Y=input()
    lenX=len(X)
    lenY=len(Y)
    Z=[[0 for i in range(lenY)] for i in range(lenX)]

    if X[0]==Y[0]:
        Z[0][0]=1
    
    for i in range(1,lenY):
        if Z[0][i-1]==1:
            Z[0][i]=1
        else:
            if Y[i]==X[0]:
                Z[0][i]=1

    for j in range(lenX):
        if Z[j-1][0]==1:
            Z[j][0]=1
        else:
            if X[j]==Y[0]:
                Z[j][0]=1


    for i in range(1,lenX):
        for j in range(1,lenY):
            x=lastindex(X[:i+1:],Y[j])
            y=lastindex(Y[:j+1:],X[i])

            if x!=-1 and y!=-1:
                Z[i][j]=max(Z[x][j-1],Z[i-1][y])+1
            elif x!=-1:
                Z[i][j]=Z[x][j-1]+1
            elif y!=-1:
                Z[i][j]=Z[i-1][y]+1

            Z[i][j]=max(Z[i][j],Z[i-1][j],Z[i][j-1])

    print(Z[-1][-1])

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


def lcs(x, y):
    n = len(x)
    m = len(y)
    return rec(x, y, n, m)


@functools.lru_cache(maxsize=None)
def rec(x, y, i, j):
    if i == 0 or j == 0:
        return 0
    elif x[i - 1] == y[j - 1]:
        return rec(x, y, i - 1, j - 1) + 1
    else:
        return max(rec(x, y, i, j - 1), rec(x, y, i - 1, j))


if __name__ == '__main__':
    import sys
    sys.setrecursionlimit(10**7)
    q = int(sys.stdin.readline().strip())
    for i in range(q):
        x = sys.stdin.readline().strip()
        y = sys.stdin.readline().strip()
        print(lcs(x, y))