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 <iostream>
#include <algorithm>

#define rep(i, n) for(int i = 0; i < (n); ++i)

using namespace std;

string s, t;
int dp[4001][4001];

int main(){
	while(cin >> s >> t){
		rep(i, s.size() + 1){
			dp[i][0] = 0;
		}
		rep(i, t.size() + 1){
			dp[0][i] = 0;
		}
		for(int i = 1; i <= s.size(); ++i){
			for(int j = 1; j <= t.size(); ++j){
				dp[i][j] = s[i - 1] == t[j - 1] ? dp[i - 1][j - 1] + 1 : 0;
			}
		}
		int ans = 0;
		rep(i, s.size()){
			ans = max(*max_element(dp[i], dp[i] + t.size() + 1), ans);
		}
		cout << ans << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include<cmath>
#include<queue>
#include<map>
#include<set>
#include<list>
#include<iomanip>
#include<vector>
#include<functional>
#include<algorithm>
#include<cstdio>
#include<unordered_map>
using namespace std;
typedef long long ll;
vector<int>v[26][2];
int main() {
	string a, b;
	while (cin >> a >> b) {
		for (int i = 0; i < 26; i++) {
			v[i][0].clear();
			v[i][1].clear();
		}
		for (int i = 0; i < a.length(); i++) {
			int k = (int)a[i] - 'A';
			v[k][0].push_back(i);
		}
		for (int i = 0; i < b.length(); i++) {
			int k = (int)b[i] - 'A';
			v[k][1].push_back(i);
		}
		int sum = 0;
		for (int i = 0; i < 26; i++) {
			for (int j = 0; j < v[i][0].size(); j++) {
				for (int x = 0; x < v[i][1].size(); x++) {
					int a2 = v[i][0][j], b2 = v[i][1][x];
					int sum2 = 0;
					while (a[a2] == b[b2]&&a2<a.length()&&b2<b.length()) {
						sum2++;
						a2++;
						b2++;
					}
					sum = max(sum, sum2);
				}
			}
		}
		cout << sum << endl;
	}
}

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

string s, t;
char tmp[4001];
int dp[4001][4001];

int main(){
	while(1){
		scanf("%s", tmp);
		if(tmp[0] == EOF) break;

		s = tmp;
		scanf("%s", tmp);
		t = tmp;

		for(int i=0; i<4001; i++)
			for(int j=0; j<4001; j++)
				dp[i][j] = 0;

		int ans = 0;
		for(int i=1; i<s.size(); i++){
			for(int j=1; j<t.size(); j++){
				if(s[i-1] == t[j-1]){
					dp[i][j] = dp[i-1][j-1]+1;
				}else{
					dp[i][j] = 0;
				}
				ans = max(ans, dp[i][j]);
			}
		}

		printf("%d\n", ans);
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define Rep(i,N) for(int i = 0; i < N; i++)

int main()
{
  string S, W;
  while(cin >> S >> W) {
    int dp[4005] = {0};
    int maxv = 0;
    Rep(i,W.size()) {
      for(int j = S.size(); j > 0; j--) {
	if(S[j - 1] == W[i]) {
	  dp[j] = dp[j - 1] + 1;
	  maxv = max(maxv, dp[j]);
	} else dp[j] = 0;
      }
    }
    cout << maxv << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main(){
	string a,b;
	while(cin>>a>>b){
		int n=0;
		int la=a.size();
		int lb=b.size();
		for(int i=1-la;i<lb;i++){
			int k=0;
			for(int j=0;j<la;j++){
				if(j+i<0||j+i>lb-1){
					k=0;
				}
				else if(a[j]==b[j+i]){
					k++;
					n=max(n,k);
				}
				else{
					k=0;
				}
			}
		}
		cout<<n<<endl;
	}
    return 0;
}

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

int cnt[4001][4001];

int main(){
	string a, b;
	int na, nb;

	cin >> a >> b;
	na = a.length();
	nb = b.length();

	for(int i=0; i<na+1; i++){
		cnt[i][0] = 0;
	}
	for(int j=0; j<nb+1; j++){
		cnt[0][j] = 0;
	}

	int mx = 0;
	for(int i=0; i<na; i++){
		for(int j=0; j<nb; j++){
			if(a[i]==b[j]){
				cnt[i+1][j+1] = cnt[i][j] + 1;
				if(mx < cnt[i+1][j+1]){
					mx = cnt[i+1][j+1];
				}
			}else{
				cnt[i+1][j+1] = 0;
			}
		}
	}
	cout << mx << endl;
	return 0;
}

C++: #include <iostream>
#include <string>
#include <cstring>
int dp[4001][4001];
using namespace std;
int main(){
  string s,str;
  int ans = 0;
  while(cin >> s >> str){
    memset(dp,0,sizeof(dp));
    for(int i=0,l=s.size();i<l;i++){
      for(int j=0,ll=str.size();j<ll;j++){
        if(s[i] == str[j]){
          dp[i+1][j+1] = dp[i][j]+1;
          ans = max(ans,dp[i+1][j+1]);
        }else dp[i+1][j+1] = 0;
      }
    }
    cout << ans << endl;
  }
}

C++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define forever for (;;)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
template<typename A> using V = std::vector<A>;
template<typename A> using F = std::function<A>;
template<typename A, typename B> using P = std::pair<A, B>;
using pii = P<int, int>;
using vi = V<int>;
using vd = V<double>;
using vs = V<std::string>;
using vpii = V<pii>;
using vvi = V<vi>;
using vvpii = V<vpii>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = 3.14159265358979;
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
constexpr bool odd(const int n) { return n & 1; }
constexpr bool even(const int n) { return ~n & 1; }
template<typename T> std::istream &operator>>(std::istream &is, std::vector<T> &v) { for (T &x : v) is >> x; return is; }
template<typename A, typename B> std::istream &operator>>(std::istream &is, std::pair<A, B> &p) { is >> p.first; is >> p.second; return is; }
using namespace std;
// clang-format on

main {
  string s, t;
  while (cin >> s >> t) {
    vvi dp(s.size() + 1, vi(t.size() + 1));
    int maxi = 0;
    rep(i, s.size()) rep(j, t.size()) {
      if (s[i] == t[j]) dp[i + 1][j + 1] = dp[i][j] + 1;
      cmax(maxi, dp[i + 1][j + 1]);
    }
    cout << maxi << endl;
  }
}

C++: #include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <queue>
#include <cmath>
#include <set>
#include <map>
#include <iostream>

using namespace std;
typedef long long ll;


int n;
char A[4001],B[4001];

void calc(){
    int an,bn,p,ans=0;
    
    for(an=0;A[an]!='\0';an++);
    for(bn=0;B[bn]!='\0';bn++);
    
    for(int i=0;i<an;i++){
        p=0;
        for(int j=0;j<bn && i+j<an;j++){
            
            if(A[i+j]==B[j]){
                p++;
                ans=max(ans,p);
            }else{
                p=0;
            }
        }
    }
    
    printf("%d\n",ans);
    
    return;
}

int main(){
    string in1,in2;
    
    while(scanf("%s%s",A,B)!=EOF){
        calc();
    }
    
    return 0;
}