#include <iostream>
#include <cstdio>
#include <algorithm>

using namespace std;

const int N = 1010;

int n, m;
char a[N], b[N];
int f[N][N];

int main() {
    cin >> n >> m >> a+1 >> b+1; //从下标1开始读入

    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j <= m; ++j) { //计算f[i][j]
            f[i][j] = max(f[i-1][j], f[i][j-1]); //求出第②种情况与第③种情况的最大值
            if (a[i] == b[j]) //第④种情况只有在a_i=b_j的情况下才存在
                f[i][j] = max(f[i][j], f[i-1][j-1]+1);
        }
    }

    printf("%d", f[n][m]); //根据定义可知答案是f_n,m
    return 0;
}