JavaScript Solution. Beginner friendly
Time Complexity : O(n*m)\nWhere n : length of array of words; m : length of that particular word;\n\n/**\n * @param {string} allowed\n * @param {string[]} words
**Time Complexity : O(n*m)**\nWhere n : length of array of words; m : length of that particular word;\n```\n/**\n * @param {string} allowed\n * @param {string[]} words\n * @return {number}\n */\nvar countConsistentStrings = function(allowed, words) {\n    let count = 0;\n    for(const word of words){\n        for(let i=0; i<word.length; i++){\n            if(!allowed.includes(word[i])){\n                count++;\n                break;\n            }\n        }\n    }\n    return words.length - count;\n};\n```
['JavaScript']