YES(?, a + b + 7)

Initial complexity problem:
1:	T:
		(?, 1)    f2(a, b, c) -> f2(a + 1, b + 1, c) [ 1 >= a ]
		(?, 1)    f2(a, b, c) -> f2(a + 1, b + 1, c) [ 2 >= b /\ a >= 2 ]
		(?, 1)    f2(a, b, c) -> f300(a, b, d) [ b >= 3 /\ a >= 2 ]
		(1, 1)    f1(a, b, c) -> f2(a, b, c)
	start location:	f1
	leaf cost:	0

Repeatedly removing leaves of the complexity graph in problem 1 produces the following problem:
2:	T:
		(?, 1)    f2(a, b, c) -> f2(a + 1, b + 1, c) [ 1 >= a ]
		(?, 1)    f2(a, b, c) -> f2(a + 1, b + 1, c) [ 2 >= b /\ a >= 2 ]
		(1, 1)    f1(a, b, c) -> f2(a, b, c)
	start location:	f1
	leaf cost:	1

A polynomial rank function with
	Pol(f2) = -V_2 + 3
	Pol(f1) = -V_2 + 3
orients all transitions weakly and the transition
	f2(a, b, c) -> f2(a + 1, b + 1, c) [ 2 >= b /\ a >= 2 ]
strictly and produces the following problem:
3:	T:
		(?, 1)        f2(a, b, c) -> f2(a + 1, b + 1, c) [ 1 >= a ]
		(b + 3, 1)    f2(a, b, c) -> f2(a + 1, b + 1, c) [ 2 >= b /\ a >= 2 ]
		(1, 1)        f1(a, b, c) -> f2(a, b, c)
	start location:	f1
	leaf cost:	1

A polynomial rank function with
	Pol(f2) = -V_1 + 2
	Pol(f1) = -V_1 + 2
orients all transitions weakly and the transition
	f2(a, b, c) -> f2(a + 1, b + 1, c) [ 1 >= a ]
strictly and produces the following problem:
4:	T:
		(a + 2, 1)    f2(a, b, c) -> f2(a + 1, b + 1, c) [ 1 >= a ]
		(b + 3, 1)    f2(a, b, c) -> f2(a + 1, b + 1, c) [ 2 >= b /\ a >= 2 ]
		(1, 1)        f1(a, b, c) -> f2(a, b, c)
	start location:	f1
	leaf cost:	1

Complexity upper bound a + b + 7

Time: 0.194 sec (SMT: 0.184 sec)