// dfmt off
T lread(T=long)(){return readln.chomp.to!T;}T[] lreads(T=long)(long n){return iota(n).map!((_)=>lread!T).array;}
T[] aryread(T=long)(){return readln.split.to!(T[]);}void arywrite(T)(T a){a.map!text.join(' ').writeln;}
void scan(L...)(ref L A){auto l=readln.split;foreach(i,T;L){A[i]=l[i].to!T;}}alias sread=()=>readln.chomp();
void dprint(L...)(lazy L A){debug{auto l=new string[](L.length);static foreach(i,a;A)l[i]=a.text;arywrite(l);}}
alias PQueue(T,alias l="b<a")=BinaryHeap!(Array!T,l);import std, core.bitop;
// dfmt on
void main()
{
    auto input = stdin.byLine.map!split.joiner;

    long L;
    L = input.front.to!long;
    input.popFront;

    long R;
    R = input.front.to!long;
    input.popFront;

    long d;
    d = input.front.to!long;
    input.popFront;

    solve(L, R, d);
}

void solve(long L, long R, long d)
{
    writeln(R / d - (L - 1) / d);
}
