Go: package main

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

const (
	initialBufSize = 100000
	maxBufSize     = 1000000
)

var sc *bufio.Scanner

func initScanner(r io.Reader) *bufio.Scanner {
	buf := make([]byte, initialBufSize)

	sc := bufio.NewScanner(r)
	sc.Buffer(buf, maxBufSize)
	sc.Split(bufio.ScanWords) // bufio.ScanLines
	return sc
}

func main() {
	sc = initScanner(os.Stdin)
	resolve()
}

func resolve() {
	n := scanInt(sc)
	results := []int{}
	for i := 0; i < n; i++ {
		results = append(results, resolveInstance())
	}
	for _, v := range results {
		fmt.Println(v)
	}
	return
}

func resolveInstance() int {
	x, y := scanString(sc), scanString(sc)
	lx, ly := len(x), len(y)
	dp := make([][]int, lx+1)
	dp[0] = make([]int, ly+1)
	for i := 1; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
		dp[i][0] = dp[i-1][0]
		for j := 1; j <= ly; j++ {
			dp[i][j] = dp[i-1][j]
			if dp[i][j] < dp[i][j-1] {
				dp[i][j] = dp[i][j-1]
			}
			if x[i-1] == y[j-1] {
				cL := dp[i-1][j-1] + 1
				if dp[i][j] < cL {
					dp[i][j] = cL
				}
			}
		}
	}
	return dp[lx][ly]
}

const (
	remove = 0 + iota
	match
)

// snip-scan-funcs
func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return int(i)
}
func scanString(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

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

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

static const int N = 100;

int lcs(string X, string Y);

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

// longest common sequence
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;
	int i, j;
	FOR(i, 1, m + 1) FOR(j, 1, n + 1) {
		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;
}

C++: #include<iostream>
#include<iomanip>
#include<algorithm>
#include<bitset>
#include<cctype>
#include<climits>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<deque>
#include<list>
#include<map>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<queue>
#include<vector>
using namespace std;

#define MAX 1001

static int dp[MAX][MAX];

int main() {
	int q; cin >> q;
	while (q--) {
		memset(dp, 0, sizeof(dp));
		string X, Y; cin >> X >> Y;
		for (int i = 1; i <= X.size(); i++) {
			for (int j = 1; j <= Y.size(); j++) {
				if (X[i - 1] == Y[j - 1]) {
					//cout << i << j << X[i - 1] << endl;
					dp[i][j] = dp[i - 1][j - 1] + 1;
				}
				else {
					dp[i][j] = max(
						dp[i - 1][j],
						dp[i][j - 1]
					);
				}
			}
		}
		//for (int i = 0; i <= Y.size(); i++) {
		//	for (int j = 0; j <= X.size(); j++) {
		//		cout << dp[j][i] << " ";
		//	}
		//	cout << endl;
		//}
		cout << dp[X.size()][Y.size()] << endl;

	}

	return 0;
}

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

int lcs(string &X, string &Y)
{
	static int Z[1001][1001];
	int m = X.size();
	int n = Y.size();
	int i, j;

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

int main()
{
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);

	string X, Y;
	int q;
	cin >> q;
	for (int i = 0; i < q; i++) {
		cin >> X >> Y;
		cout << lcs(X, Y) << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <string>
#include <cstring>
#include <fstream>
#include <cmath>
#include <iomanip>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <map>
#include <deque>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <list>
#include <unordered_map>



using namespace std;

const int N = 1000;
int c[N+1][N+1];
    
int lcs(string X, string Y){
    int m = X.size();
    int n = Y.size();
    int maxl = 0;
    X = ' ' + X;
    Y = ' ' + Y;
    for (int i=1;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][j-1],c[i-1][j]);
            }
            maxl = max(maxl,c[i][j]);
        }
    }
    return maxl;
}

int main() {
    

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


}

C++: #include<iostream>
#include<string>
int main()
{
  int n;
  int an[1000];
  int l=0;
  std::cin>>n;
  std::string x;
  std::string y;
  int ans[1000][1000];
  int j,k;
  for(int i=0;i<n;i++){
    std::cin>>x;
    std::cin>>y;
    for(int j=0;j<1000;j++){
      for(int k=0;k<1000;k++){
	ans[j][k]=0;
      }
    }
    for(int j=0;j<x.size();j++){
      for(int k=0;k<y.size();k++){
	if(x[j]==y[k]){
	  ans[j][k]=ans[j-1][k-1]+1;
	}else{
	  if(ans[j][k-1]>ans[j-1][k]){
	    ans[j][k]=ans[j][k-1];
	  }else{
	    ans[j][k]=ans[j-1][k];
	  }
	}
      }
    }
    std::cout<<ans[x.size()-1][y.size()-1]<<'\n';  
  }
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
#define P(x) cout << (x) << endl
#define p(x) cout << (x)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define vv(type, c, m, n, i) vector<vector<type>> c(m, vector<type>(n, i));
#define rep(i,a,n) for(int i=(a), i##_len=(n); i<i##_len; ++i)
#define rrep(i,a,n) for(int i=(a), i##_len=(n); i>i##_len; --i)
#define len(x) ((int)(x).size())
#define mp make_pair
#define eb emplace_back
typedef long long ll;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<long long> vll;
typedef vector<string> vs;
typedef vector<bool> vb;
constexpr int MAX = 1005;
inline void lcs(string X, string Y) {
	vv(int, dp, MAX, MAX, 0);
	int len_X = len(X);
	int len_Y = len(Y);
	rep(i, 0, len_X) {
		rep(j, 0, len_Y) {
			dp[i + 1][j + 1] = (X[i] == Y[j] ? dp[i][j] + 1 : max(dp[i][j + 1], dp[i + 1][j]));
		}
	}
	P(dp[len_X][len_Y]);
}
int main() {
	int n; cin >> n;
	string s1, s2;
	rep(i, 0, n) {
		cin >> s1 >> s2;
		lcs(s1, s2);
	}
	return 0;
}

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

string X;
string Y;

int calc(int x, int y){
    if (X[x] == '\0') return 0;
    int y_ = Y.find(X[x], y);
    if (y_ == string::npos) {
        return 0;
    }
    int ret = 1;
    int tmp1 = calc(x,     y + 1);
    int tmp2 = calc(x + 1, y + 1);
    ret += max(tmp1, tmp2);
    return ret;

    // if (X[x] == '\0') return length;
    // int y_ = Y.find(X[x], y);
    // if (y_ == string::npos) {
    //     if ((Y[y+1] == '\0')) {
    //         return max(length, calc(x_s + 1, x_s + 1, 0, 0));
    //     }
    // }
    // int tmp1 = calc(x_s, x, y + 1, length);
    // int tmp2 = calc(x_s, x + 1, y_ + 1, length + 1);
    // return max(tmp1, tmp2);
}

int main(){
    int q;
    cin >> q;
    for (int i = 0; i < q; i++) {
        cin >> X;
        cin >> Y;
        cout << calc(0, 0) << endl;
    }

    return 0;
}