The answer is 22 how it workss [duplicate]

This question already has an answer here:

• Why are these constructs (using ++) undefined behavior in C? 13 answers

Explain the output of this code:

#include <stdio.h>
int main(void) 
{
    int I=5; 
    int a = ++I + ++I + ++I;
    printf("%d", a); 
    return 0;
}