Go: package main

import (
	"bufio"
	"os"
	"io"
	"strconv"
	"math"
	"fmt"
)

var (
	nstr   func() string
	stdout *bufio.Writer
)

func init() {
	nstr = newReadString(os.Stdin)
	stdout = bufio.NewWriter(os.Stdout)
}

func main() {
	defer stdout.Flush()

	n := nint()
	xList := make([]string, n)
	yList := make([]string, n)

	for i:=0;i<n ;i++  {
		xList[i] = nstr()
		yList[i] = nstr()
	}

	for i := 0; i<n	; i++  {
		fmt.Println(lcs(xList[i], yList[i]))
	}

}

func lcs(x string, y string) int{
	var m = len(x)
	var n = len(y)

	c := make([][]int, m+1)
	for i:= range c{
		c[i] = make([]int, n+1)
	}
	for i:=	1;i<=m ;i++  {
		for j:=1;j<=n ;j++  {
			if x[i-1] == y[j-1]{
				c[i][j] = c[i-1][j-1] + 1
			}else{
				c[i][j] = int(math.Max(float64(c[i-1][j]), float64(c[i][j-1])))
			}


		}
	}
	return c[m][n]

}


func newReadString(ior io.Reader) func() string {
	r := bufio.NewScanner(ior)
	r.Buffer(make([]byte, 1024), int(1e+11))
	r.Split(bufio.ScanWords)

	return func() string {
		if !r.Scan() {
			panic("Scan failed")
		}
		return r.Text()
	}
}

func nint64() int64 {
	i, err := strconv.ParseInt(nstr(), 0, 64)
	if err != nil {
		panic(err.Error())
	}
	return i
}

func nint() int {
	return int(nint64())
}

func getIntSlice(n int) []int {
	b := make([]int, n)
	for i := 0; i < n; i++ {
		b[i] = nint()
	}
	return b
}

func getStringSlice(n int) []string {
	b := make([]string, n)
	for i := 0; i < n; i++ {
		b[i] = nstr()
	}
	return b
}

func gcd(x, y int) int {
	if y == 0 {
		return x
	}
	return gcd(y, x%y)
}

func lcm(x, y int) int {
	return x * y / gcd(x, y)
}

func contains(s []int, e int) bool {
	for _, a := range s {
		if a == e {
			return true
		}
	}
	return false
}

func bin(i int, prefix bool) string {
	i64 := int64(i)

	if prefix {
		return "0b" + strconv.FormatInt(i64, 2)
	} else {
		return strconv.FormatInt(i64, 2)
	}
}

func strReverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}

	return string(runes)
}

C++: #include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
#define all(x) (x).begin(),(x).end()
#define rep(i,n) for(int (i)=0;i<(n);i++)
#define REP(i,m,n) for(int (i)=(m);(i)<(n);(i)++)
#define INF LLONG_MAX - 100
#define MOD 1000000007
#define fcout cout << fixed << setprecision(15)
#define int long long
#define yorn(f) puts((f)?"Yes":"No")
#define YORN(f) puts((f)?"YES":"NO")
#define lower_bound lowb
#define upper_bound upb
typedef long long ll;
typedef pair<int, int> P;
typedef priority_queue<int> pque;
int gcd(int a,int b){return b?gcd(b,a%b):a;};
int lcm(int a,int b){return a*b/gcd(a,b);};
int mod(int a,int b){return (a+b-1)/b;};
template<typename A, size_t N, typename T>
void Fill(A(&array)[N],const T &val){std::fill((T*)array,(T*)(array+N),val);}
template<class T>inline bool chmax(T& a,T b){if(a<b){a=b;return true;}return false;};
template<class T>inline bool chmin(T& a,T b){if(a>b){a=b;return true;}return false;};

int dp[2010][2010];

int LCS(string s, string t) {
    rep(i, s.size() + 10) dp[i][0] = 0;
    rep(i, t.size() + 10) dp[0][i] = 0;

    for(int i = 1; i <= s.size(); i++) {
        for(int j = 1; j <= t.size(); j++) {
            dp[i][j] = 0;
            chmax(dp[i][j], dp[i - 1][j]);
            chmax(dp[i][j], dp[i][j - 1]);

            if(s[i - 1] == t[j - 1]) {
                chmax(dp[i][j], dp[i - 1][j - 1] + 1);
                //cout << "foo" << endl;
            }
        }
    }
    
    return dp[s.size()][t.size()];
}

signed main() {
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(false);

    int q;
    cin >> q;
    rep(i, q) {
        string s, t;
        cin >> s >> t;
        cout << LCS(s, t) << endl;
    }
    return 0;
}

C++: #include<iostream>
using namespce std;

int main()
{
	int n,i;
	int a[25];
	cin >> n;
	for(i=0;i<n;i++){
		cin >> a[i];
	}
}

C++: #include <iostream>
#include <iomanip>
#include <algorithm>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <functional>
#include <sstream>
#include <string>
#include <utility>
#include <map>
#include <memory>
#include <set>
#include <vector>
#include <deque>
#include <list>
#include <stack>
#include <queue>
#include <array>

using namespace std;

class LCSubseq
{
public:
  int solve( const string x, const string y );
};

int LCSubseq::solve( const string x, const string y )
{
  vector<vector<int>> dp( 1 + x.size(), vector<int>( 1 + y.size(), 0 ) );
  
  for ( auto i = 0; i < (int)x.size(); ++i )
    for( auto j = 0; j < (int)y.size(); ++j )
      {
        if ( x[i] == y[j] )
          dp[i+1][j+1] = dp[i][j] + 1;
        else
          dp[i+1][j+1] = max( dp[i+1][j], dp[i][j+1] );
      }
  
  cout << dp[x.size()][y.size()] << endl;
  
  return 0;
}

int main()
{
  int n;
  cin >> n;

  LCSubseq l;

  string x, y;
  
  for ( auto i = 0; i < n; ++i )
    {
      cin >> x;
      cin >> y;
      l.solve( x, y );
    }
  
  return 0;
}

C++: #include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
#include<stack>
#include<queue>
#include<vector>
#include<algorithm>
#include<string>
#include<iostream>
using namespace std;
static const int N=1000;
/*int max(int a,int b){
    if(a>b)return a;else return b;
}*/
int lcs(string X,string Y){
    int c[N+1][N+1];
    int m=X.size();
    int n=Y.size();
    int maxl=0;
    X=' '+X;
    Y=' '+Y;
    for(int i=0;i<=m;i++)c[i][0]=0;
    for(int j=1;j<=n;j++)c[0][j]=0;
    
    for(int i=1;i<=m;i++){
        for(int j=1;j<=n;j++){
            if(X[i]==Y[j]){
                c[i][j]=c[i-1][j-1]+1;
            }else{
                c[i][j]=max(c[i-1][j],c[i][j-1]);
            }
            maxl=max(maxl,c[i][j]);
        }
    }
    return maxl;
}

int main(){
    string s1,s2;
    int n;cin>>n;
    for(int i=0;i<n;i++){
        cin>>s1>>s2;
        cout<<lcs(s1,s2)<<endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
#define REP(i,n) for(int i=0;i<n;i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define ALL(s) (s).begin(), (s).end()
#define ALLA(a) a,a+a.size();
using namespace std;
typedef long long unsigned int llu;
typedef long long ll;


int lcs(string X,string Y){
  int m = X.length();
  int n = Y.length();
  int c[m+1][n+1];
  int maxl = 0;
  //0文字目を追加1-indexed
  X = ' ' + X;
  Y = ' ' + Y;
  //0文字目と一致するはずがないので0を入れる
  REP(i,m + 1){
    c[i][0] = 0;
  }
  REP(j,n + 1){
    c[0][j] = 0;
  }

  //Xの1文字ずつループ
  FOR(i,1,m+1){
    //Yの1文字ずつループ
    FOR(j,1,n+1){
      if(X[i] == Y[j]){
	/*XとYで一致する文字を見つけた
	  ⇛ その文字が出るまでのLCSに1を足す(新たな文字)*/
	c[i][j] = c[i-1][j-1] + 1;
      }else{
	c[i][j] = max(c[i-1][j],c[i][j-1]);
      }
      
      maxl = max(maxl, c[i][j]);
    }

  }
  return maxl;
}

int main (){
  int n;
  string x,y;
  while (cin >> n){
    REP(i,n){
      cin >> x >> y;
      cout << lcs(x,y) << endl;
    }
    
  }
  return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std;

static const int N = 1000;

int lcs(string X, string Y){
  int c[N+1][N+1];
  int m = X.size();
  int n = Y.size();
  int maxl = 0;
  X = ' ' + X;
  Y = ' ' + Y;
  for(int i=0;i<=m;i++) c[i][0] = 0;
  for(int j = 1;j<=n;j++) c[0][j] = 0;

  for(int i = 1;i <= m;i++){
    for(int j = 1;j <= n;j++){
      if(X[i] == Y[j]){
	c[i][j] = c[i-1][j-1] + 1;
      }else{
	c[i][j] = max(c[i-1][j], c[i][j-1]);
      }
      maxl = max(maxl, c[i][j]);
    }
  }

  return maxl;
}

int main(){
  string s1,s2;
  int n;
  cin >> n;
  for(int i=0;i<n;i++){
    cin >> s1 >> s2;
    cout << lcs(s1,s2) << endl;
  }
  return 0;
}