2255. Count Prefixes of a Given String

class Solution {
public:
    int countPrefixes(vector<string>& words, string s) 
    {
        int cnt = 0, n = s.length();
        for(int i=0; i<words.size(); i++)
        {
            int j = 0, m = words[i].length(), k = 0, a = 0;
            while(j<m && k<n && n>=m)
            {
                if(words[i][j]==s[k])
                {
                    a = 1;
                }
                else
                {
                    a = 0;
                    break;
                }
                j++;
                k++;
                
            }
            if(a == 1)  cnt++;
        }
        return cnt;
    }
};