Codeforces B. Delete from the Left 1005B

A solution in c++

#include<bits/stdc++.h>

using namespace std;

/// Typedef
typedef long long int ll;


//Int data type
#define sc1(a)              scanf("%d", &a)
#define sc2(a, b)           scanf("%d %d", &a, &b)
#define sc3(a, b, c)        scanf("%d %d %d", &a, &b, &c)
#define sc4(a, b, c, d)     scanf("%d %d %d %d", &a, &b, &c, &d)

//Long Data type
#define scl1(a)             scanf("%lld", &a)
#define scl2(a, b)          scanf("%lld %lld", &a, &b)
#define scl3(a, b, c)       scanf("%lld %lld %lld", &a, &b, &c)
#define scl4(a, b, c, d)    scanf("%lld %lld %lld %lld", &a, &b, &c, &d)

#define mx 100000000
#define pf(a) cout<<a<<endl


int main()
{
    ll n,m,i,j,k=0,ck=0,dk=0,a,b;

    string arr,brr;
    cin>>arr>>brr;

    i = arr.size()-1;
    j = brr.size()-1;

    while(i>=0 && j>=0){
        if(arr[i]==brr[j])
            ck+=2;
        else break;
            i--, j--;
    }
    a = arr.size()+brr.size();
    cout<<a-ck<<endl;
}