very simple C solution
\n\n#include <string.h>\nint countConsistentStrings(char * allowed, char ** words, int wordsSize){\n\tint count = 0;\n    for(int i = 0; i < wordsSize; i++){\n 
```\n\n#include <string.h>\nint countConsistentStrings(char * allowed, char ** words, int wordsSize){\n\tint count = 0;\n    for(int i = 0; i < wordsSize; i++){\n        if(strspn(words[i], allowed) == strlen(words[i])){\n            count++;\n        }\n    }\n    return count;\n}\n```
['String', 'C']