Go: ///
// File:  0528.go
// Author: ymiyamoto
//
// Created on Thu Mar 22 01:52:09 2018
//
package main

import (
	"bufio"
	"fmt"
	"os"
)

var S, T string
var dp [4001][4001]int

func max(a, b int) int {
	if a < b {
		return b
	}
	return a
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	for {
		scanner.Scan()
		S = scanner.Text()
		if len(S) == 0 {
			return
		}

		scanner.Scan()
		T = scanner.Text()

		for i := range dp {
			for j := range dp[i] {
				dp[i][j] = 0
			}
		}

		dp[0][0] = 0
		for i := range S {
			for j := range T {
				if S[i] == T[j] {
					dp[i+1][j+1] = max(dp[i+1][j], max(dp[i][j+1], dp[i][j]+1))
				} else {
					dp[i+1][j+1] = 0
				}
			}
		}
		var m int
		for i := range dp {
			for j := range dp[i] {
				m = max(m, dp[i][j])
			}
		}
		fmt.Println(m)
	}
}

C++: #include <string>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
class SuffixArray {
	void CEB(vector<int> &v, vector<int> &b) {
		int vs = v.size(), bs = b.size();
		fill(b.begin(), b.end(), 0);
		for (int i = 0; i < vs; i++) b[v[i]]++;
		for (int i = 1; i < bs; i++) b[i] += b[i - 1];
	}
	void ISort(vector<int> &v, vector<int> &SA, int mv, vector<int> &b, vector<int> &isL) {
		int vs = v.size(), bs = b.size();
		fill(b.begin(), b.end(), 0);
		for (int i = 0; i < vs; i++) b[v[i]]++;
		int sum = 0;
		for (int i = 0; i < bs; i++) b[i] += sum, swap(sum, b[i]);
		for (int i = 0; i < vs; i++) {
			if (SA[i] > 0 && isL[SA[i] - 1]) SA[b[v[SA[i] - 1]]++] = SA[i] - 1;
		}
	}
	void IISort(vector<int> &v, vector<int> &SA, int mv, vector<int> &b, vector<int> &isL) {
		CEB(v, b);
		for (int i = v.size() - 1; i >= 0; i--) {
			if (SA[i] > 0 && !isL[SA[i] - 1]) SA[--b[v[SA[i] - 1]]] = SA[i] - 1;
		}
	}
	vector<int>SA_IS(vector<int> v, int mv) {
		int vs = v.size();
		if (vs == 1) return vector<int>(1, 0);
		vector<int> isL(vs), b(mv + 1), SA(vs, -1), ord(vs);
		auto isLMS = [&](int x)->bool { return x > 0 && isL[x - 1] && !isL[x]; };
		for (int i = vs - 2; i >= 0; i--) isL[i] = (v[i] > v[i + 1]) || (v[i] == v[i + 1] && isL[i + 1]);
		CEB(v, b);
		for (int i = 0; i < vs; i++) {
			if (isLMS(i)) SA[--b[v[i]]] = i;
		}
		ISort(v, SA, mv, b, isL);
		IISort(v, SA, mv, b, isL);
		int cur = 0;
		for (int i = 0; i < vs; i++) {
			if (isLMS(i)) ord[i] = cur++;
		}
		vector<int> nxv(cur);
		cur = -1;
		int prev = -1;
		for (int i = 0; i < vs; i++) {
			if (!isLMS(SA[i])) continue;
			bool diff = false;
			for (int d = 0; d < vs; d++) {
				if (prev == -1 || v[SA[i] + d] != v[prev + d] || isL[SA[i] + d] != isL[prev + d]) {
					diff = true;
					break;
				}
				else if (d && isLMS(SA[i] + d))break;
			}
			if (diff) cur++, prev = SA[i];
			nxv[ord[SA[i]]] = cur;
		}
		vector<int> reord(nxv.size());
		for (int i = 0; i < vs; i++) {
			if (isLMS(i)) reord[ord[i]] = i;
		}
		vector<int> nxSA = SA_IS(nxv, cur);
		CEB(v, b);
		for (int i = 0; i < SA.size(); i++) SA[i] = -1;
		for (int i = nxSA.size() - 1; i >= 0; i--) {
			SA[--b[v[reord[nxSA[i]]]]] = reord[nxSA[i]];
		}
		ISort(v, SA, mv, b, isL);
		IISort(v, SA, mv, b, isL);
		return SA;
	}
	vector<int>SA_IS(string s) {
		vector<int> v(s.size() + 1);
		for (int i = 0; i < s.size(); i++) v[i] = s[i] + 1;
		return SA_IS(v, *max_element(v.begin(), v.end()));
	}
	vector<int>construct_lcp(string &s, vector<int> &sa) {
		vector<int> lcp, rank(s.size() + 1);
		int n = s.size(), h = 0;
		for (int i = 0; i <= n; i++) rank[sa[i]] = i;
		for (int i = 0; i < n; i++) {
			int j = sa[rank[i] - 1];
			if (h) h--;
			for (; j + h < n && i + h < n; h++) {
				if (s[j + h] != s[i + h]) break;
			}
			lcp[rank[i] - 1] = h;
		}
		return lcp;
	}
public:
	string s;
	vector<int> sa, lcp;
	void init(string &T) {
		s = T;
		sa = SA_IS(s);
		lcp = construct_lcp(s, sa);
	}
	SuffixArray(string &t) { init(t); }
	SuffixArray() {}
	bool contain(string &t) {
		int a = 0, b = s.size();
		while (b - a > 1) {
			int c = (a + b) / 2;
			if (s.compare(sa[c], t.size(), t) < 0) a = c;
			else b = c;
		}
		return s.compare(sa[b], t.size(), t) == 0;
	}
};
string s, t;
int main() {
	while(cin >> s >> t) {
		int sl = s.size(); s += '$' + t;
		SuffixArray v(s);
		int ret = 0, e = s.size();
		for(int i = 0; i < e; i++) {
			if((v.sa[i] < sl) != (v.sa[i + 1] < sl)) ret = max(ret, v.lcp[i]);
		}
		cout << ret << endl;
	}
}

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

int main(){
	string str1, str2;
	while(cin >> str1){
		cin >> str2;
		int count = 0;
		for(int i = 0; i < str1.size(); i++){
			for(int j = 0; j < str2.size(); j++){
				int k = 0;
				while(str1[i+k] == str2[j+k] && i+k < str1.size() && j+k < str2.size()){
					//if(i + k > str1.size()-1 || j + k > str2.size()-1) break;
					k++;
					count = max(count, k);
					//cout << str2.substr(i, k) << endl;
				}
			}
		}
		cout << count << endl;
	}
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define ll long long
int main(void){
	ll la,lb,i,j,cnt,mx,p,pp,ii;
	char a[4001],b[4001],aa[4001],bb[4001];
	while(scanf("%s",a)!=EOF){
		cin>>b;
		la=strlen(a);
		lb=strlen(b);
		if(la<=lb){
			strcpy(aa,a);
			strcpy(bb,b);
		}
		else{
			swap(la,lb);
			strcpy(bb,a);
			strcpy(aa,b);
		}
		mx=0;
//		cout<<"AAAAAAAAAAAAAAAAAAAAAAAAA"<<endl;
		for(i=1;lb-i>=0;i++){
			cnt=0;
			for(j=0;j<i;j++){
				if(bb[lb-i+j]==aa[j]) cnt++;
				else cnt=0;
				mx=max(mx,cnt);
			}
		}
		for(i=1;i<la;i++){
			cnt=0;
			for(j=0;j<lb-i;j++){
				if(aa[i+j]==bb[j]) cnt++;
				else cnt=0;
				mx=max(mx,cnt);
			}
		}
		cout<<mx<<endl;
	}
	return 0;
}

C++: //JOI 0528 Common Sub-String
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main() {
	while(1){
		string s, t; int roop1=0, save=0, ans = 0;
		cin>>s;
		cin>>t;
		if(s==""){
		break;
		}
	for (int i = 0; i<s.size(); i++){
		for (int j = 0; j<t.size(); j++){
			if (s[i] == t[j]){
				roop1 = 0;
				save= 0;
				while (1){
					if (s[i + roop1] == 0 || t[j + roop1] == 0){
						break;
					}
					else{
						if (s[i + roop1] == t[j + roop1]){
							save += 1;
							roop1++;
						}
					else if (s[i + roop1] != t[j + roop1]){
							ans=max(ans,save);
							break;
						}
					}
				}
			}
		}
	}
	cout<<ans<<endl;
	}
	
	return 0;
}

C++: //http://judge.u-aizu.ac.jp/onlinejudge/review.jsp?rid=2676345#1
//http://judge.u-aizu.ac.jp/onlinejudge/review.jsp?rid=2676345#1
#include <iostream>
#include<cstdlib>
#include<queue>
#include<set>
#include<vector>
#include<string>
#include<algorithm>
#include<stack>
#include<map>
#include<cstdio>
#include<fstream>
#include<cstring>
using namespace std;
#define rep(i,a) for(int i=0;i<a;i++)
#define mp make_pair
#define P pair<int,int>
#define ll __int64

int dp[2][5000];
int n,m;
string a,b;

int main(){
while(cin>>a>>b){
if(a.size()>b.size())swap(a,b);
n=a.size();
m=b.size();

int ans=0;
rep(i,2)rep(j,5000)dp[i][j]=0;

for(int i=0;i<n;i++){
	for(int j=0;j<m;j++){
		if(i&1){//2,4,6,8...番目
			if(a[i]==b[j]){
				dp[1][j]=dp[0][max(0,j-1)]+1;
				ans=max(ans,dp[1][j]);
			}
		}
		else{//1,3,5,7,9...番目
			if(a[i]==b[j]){
				dp[0][j]=dp[1][max(0,j-1)]+1;
				ans=max(ans,dp[0][j]);
			}
		}
	}
}

cout<<ans<<endl;
}


	return 0;
}