module.exports = function isSubstring(a, b) {
  let i = 0
  while(i < a.length - b.length){
    let j = 1
    if(a[i] == b[0]){
      while(true){
        
        if(a[i+j] == b[j]){
          if(j == b.length - 1){
            return i + j
          }
          j += 1
          continue;
        } else { break; }
      }
    }
    i += 1
  }
  return -1
}