1492C CF

#include <bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define vi vector<int>
#define vll vector<long long>
#define pb push_back
#define vpll vector<pair<ll, ll>>
#define vpi vector<pair<int, int>>
#define p_b pop_back
#define FOR(a, b) for(int i = a; i <= b; i++)
#define tests() int t; cin >> t; while(t--)
#define input(a, n) for(int i = 0; i < n; i++){int x; cin >> x; a.pb(x);}
#define MOD (ull)1000000007
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n, m, j = 0; string s, t;
    cin >> n >> m >> s >> t;
    vpi v(m, {0, 0});
    for(int i = 0; i < m; i++){
        while(j < n && s[j] != t[i]){
            j++;
        }
        v[i].first = j;
    }
    j = n-1;
    for(int i = m-1; i >= 0; i--){
        while(j >= 0 && s[j] != t[i]){
            j--;
        }
        v[i].second = j;
    }
    long ma = 0;
    for(int i = 0; i < m-1; i++){
        ma = max(ma, (long)v[i+1].second-(long)v[i].first);
    }
    cout << ma;
    return 0;
}