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] = 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 <bits/stdc++.h>

#define FOR(i,a,b) for(int i= (a); i<((int)b); ++i)
#define RFOR(i,a) for(int i=(a); i >= 0; --i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

typedef long long LL;
template<typename T> using V = std::vector<T>;
template<typename T> using VV = std::vector<std::vector<T>>;
template<typename T> using VVV = std::vector<std::vector<std::vector<T>>>;

template<class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
template<class T> inline void print(T x) { std::cout << x << std::endl; }
template<class T> inline void print_vec(const std::vector<T> &v) { for (int i = 0; i < v.size(); ++i) {  if (i != 0) {std::cout << " ";} std::cout << v[i];} std::cout << "\n"; }
template<class T> inline bool inside(T y, T x, T H, T W) {return 0 <= y and y < H and 0 <= x and x < W; }
template<class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) { return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); }
template<class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) { return abs(x1 - x2) + abs(y1 - y2); }

const int INF = 1L << 30;
const double EPS = 1e-9;
const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy4 = { 0, 1, 0, -1 }, dx4 = { 1, 0, -1, 0 };    // 4近傍（右, 下, 左, 上）
const std::vector<int> dy8 = { 0, -1, 0, 1, 1, -1, -1, 1 }, dx8 = { 1, 0, -1, 0, 1, 1, -1, -1 };

using namespace std;

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

	string s, t;
	while (cin >> s >> t) {
        vector<vector<int>> dp(5000, vector<int>(5000));
        FOR(i, 0, s.size()) {
            FOR(j, 0, t.size()) {
                if (s[i] == t[j]) {
                    dp[i + 1][j + 1] = dp[i][j] + 1;
                }
                else {
                    dp[i + 1][j + 1] = 0;
                }
            }
        }
        int ans = 0;
        FOR(i, 0, dp.size()) {
            FOR(j, 0, dp[0].size()) {
                ans = max(ans, dp[i][j]);
            }
        }
        print(ans);
	}

	return 0;
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    string s1, s2;
    while(cin >> s1 >> s2) {
        //vector<vector<int> > dp(s1.size(), vector<int>(s2.size(), 0));
        vector<int> dp[2];
        dp[0].resize(s2.size());
        dp[1].resize(s2.size());
        fill(dp[0].begin(), dp[0].end(), 0);
        fill(dp[1].begin(), dp[1].end(), 0);

        int ans = 0;
        int l1 = s1.size();
        int l2 = s2.size();
        for(int i = 0; i < l1; ++i) {
            int curr = i&1;
            int prev = 1-curr;
            for(int j = 0; j < l2; ++j) {
                if(s1[i] == s2[j]) {
                    if(i > 0 && j > 0) dp[curr][j] = dp[prev][j-1]+1;
                    else dp[curr][j] = 1;
                }
                else dp[curr][j] = 0;
                if(dp[curr][j] > ans) ans = dp[curr][j];
            }
        }
        cout << ans << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <iomanip>
#include <vector>
#include <set>
#include <map>
#include <list>
#include <iterator>
#include <queue>
#include <stack>
#include <deque>
#include <sstream>
#include <algorithm>
#include <numeric>
#include <string>
#include <cmath>
#include <complex>
#include <functional>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cassert>
#include <cstdlib>
#include <cctype>

#define REP(i,m,n) for(int i=m;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define rp(i,c) rep(i,(int)c.size())
#define fr(i,c) for(__typeof((c).begin()) i=(c).begin();i!=(c).end();i++)
#define mp make_pair
#define pb push_back
#define all(c) (c).begin(),(c).end()
#define rall(u) (u).rbegin(),(u).rend()
#define dbg(x) cerr<<#x<<" = "<<(x)<<endl
#define v_delete(a,b) (a).erase(remove((a).begin(), (a).end(), b), (a).end())
#define v_unique(a) (a).erase(unique((a).begin(), (a).end()), (a).end())
#define VV(T) vector<vector< T > >
#define init(a,b) memset((a), (b), sizeof((a)))

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pi;
const int inf=1<<28;
const double EPS=1e-9;
const long long INF = 100001000010000100ll;

template<class T>int SIZE(T a){return a.size();}
template<class T>string IntToString(T num){string res;stringstream ss;ss<<num;return ss.str();}
template<class T>T StringToInt(string str){T res=0;for(int i=0;i<SIZE(str);i++)res=(res*10+str[i]-'0');return res;}
template<class T>T gcd(T a,T b){if(b==0)return a;return gcd(b,a%b);}
template<class T>T lcm(T a,T b){return a/gcd(a,b)*b;}

template <class T> void input(T& a, int n) { for (int i = 0; i < n; ++i) cin >> a[i]; }
template <class T> void input(T* a, int n) { for (int i = 0; i < n; ++i) cin >> a[i]; }
typedef pair<int,int> pii;


string L, R;

int dp[4000+10][4000+10];

int main(){
	while(cin >> L >> R){
		memset(dp, 0, sizeof(dp));
		int ans=0;
		rp(i, R){
			rp(j, L){
				if(R[i]==L[j]){
					if(i > 0 && j > 0){
						dp[i][j] = dp[i-1][j-1] + 1;
					}else{
						dp[i][j]=1;
					}
				}else{
					dp[i][j]=0;
				}
				ans=max(ans, dp[i][j]);
			}
		}
		cout << ans << endl;
	}

	return 0;

}

C++: #include<bits/stdc++.h>
#define STR string

using namespace std;

string s,t;
long long dp[4000][4000];

void solve(){
    for(int i=0;i<s.size();i++){
        for(int j=0;j<t.size();j++){
                if(dp[i+1][j+1]=0){
            if(s[i]==t[j]){
                dp[i+1][j+1]=dp[i][j]+1;
            }else{
                dp[i+1][j+1]=(dp[i][j+1]>dp[i+1][j])?dp[i][j+1]:dp[i+1][j];
            }
        }
        }
    }
cout << dp[s.size()][t.size()] << endl;
}


int main(){
while(1){
cin >> s >>t;
if(s=="EOF")break;
solve();
}
//cout << s.size();
return 0;
}

C++: #include<iostream>
#include<cstring>
#include<string>

using namespace std;

int main(void){
	int a,b;
	while(1){
		memset(len,0,sizeof(len));
		string str;
		string str2;
		int ans=0;
		cin >> str;
		if(str=="EOF")break;
		cin >> str2;
		for(a=0;a<str.size();a++){
			int res=0;
			string tmp= str.substr(a, str.length()-a);
			for(b=0;b<min(tmp.size(),str2.size());b++){
				if(tmp[b]==str2[b])res++;
				else ans=max(res,ans),res=0;
				if(min(tmp.size(),str2.size())-1==b)ans=max(res,ans);
			}
		}
		cout << ans << endl;
	}
	return 0;
}

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

int dp[4001][4001];

int main(){
  string a,b;

  while(cin >> a >> b){
    for(int i=0;i<=(int)a.size();i++)
      for(int j=0;j<=(int)b.size();j++)dp[i][j] = 0;

    int ans = 0;
    for(int i=1;i<=(int)a.size();i++){
      for(int j=1;j<=(int)b.size();j++){
	if(a[i-1]==b[j-1]){
	  dp[i][j] = dp[i-1][j-1] + 1;
	  ans = max(ans,dp[i][j]);
	}
	//else dp[i][j] = max(dp[i][j-1],dp[i-1][j]);
      }
    }
    cout << ans << endl;
  }
}