Common Subsequence

#include<cstdio>
#include<iostream>
#include<cstring>
#include<string>
using namespace std;

int f[1010][1010];
string  str1,str2;
int main() {
    while(cin>>str1>>str2) {
        memset(f,0,sizeof(f)); 
        for(int i=1;i<=str1.size();i++) {
            for(int j=1;j<=str2.size();j++) {
                if(str1[i-1]==str2[j-1]) {
                    f[i][j]=f[i-1][j-1]+1;
                }
                else {
                    f[i][j]=max(f[i][j-1],f[i-1][j]);
                }
            }
     
         }
     
     cout<<f[str1.size()][str2.size()]<<endl;
    }
    return 0;
}