(VAR x y )
(STRATEGY INNERMOST)
(RULES 
        minus(0,x) -> 0
        minus(s(x),0) -> s(x)
        minus(s(x),s(y)) -> minus(x,y)
        mod(x,0) -> 0
        mod(x,s(y)) -> if(lt(x,s(y)),x,s(y))
        if(true,x,y) -> x
        if(false,x,y) -> mod(minus(x,y),y)
        gcd(x,0) -> x
        gcd(0,s(y)) -> s(y)
        gcd(s(x),s(y)) -> gcd(mod(s(x),s(y)),mod(s(y),s(x)))
        lt(x,0) -> false
        lt(0,s(x)) -> true
        lt(s(x),s(y)) -> lt(x,y)
        
)