How to find element inside iframe or not using selenium

Int size = driver.findElements(By.tagName("iframe")).size();

• driver.switchTo().frame(0);
• driver.switchTo().frame(1);

 for(int i=0; i<=size; i++){
 driver.switchTo().frame(i);
int total=driver.findElements(By.xpath("html/body/a/img")).size();