Pascal :

type arr=array[0..200]of longint;
var i,j,k,m,n:longint;
    ans:arr;
    a,b,d,e:arr;
    s:string;
function compare(k:longint):boolean;
var i:longint;
begin
     if a[k]=e[k] then exit(true);
     exit(false);
end;
function c(a,b:arr):arr;
var i,j:longint;
begin
     fillchar(c,sizeof(c),0);
     for i:=1 to a[0] do
     for j:=1 to b[0] do if i+j-1<=k then
     begin
          inc(c[i+j-1],(a[i]*b[j])mod 10);
          inc(c[i+j],(a[i]*b[j])div 10 +c[i+j-1] div 10);
          c[i+j-1]:=c[i+j-1] mod 10;
     end;
     c[0]:=k;
     while (c[c[0]]=0)and(c[0]>0) do dec(c[0]);
end;
function mul(k:longint):arr;
var i,j:longint;
begin
     fillchar(mul,sizeof(mul),0);
     for i:=1 to ans[0] do
     begin
          inc(mul[i],ans[i]*k);
          inc(mul[i+1],mul[i] div 10);
          mul[i]:=mul[i] mod 10;
     end;
     inc(mul[0],ans[0]+4);
     while (mul[mul[0]]=0)and(mul[0]<>0) do dec(mul[0]);
end;
begin
     ans[0]:=1; ans[1]:=1;
     readln(s);
     i:=pos(' ',s);
     for j:=i+1 to length(s) do
     k:=k*10+ord(s[j])-48;
     delete(s,i,length(s)-i+1); j:=0;
     for i:=length(s) downto 1 do
     begin
          inc(j);
          a[j]:=ord(s[i])-48;
     end;
     a[0]:=k;
     d:=a;
     e:=a;
     b[0]:=1; b[1]:=1;
     i:=1;
     j:=0;
     while true do
     begin
          if j>10 then
          begin writeln(-1); halt; end;
          inc(j);
          b:=c(b,d);
          a:=c(e,b);
          if compare(i) then
          begin
               d:=b;
               fillchar(b,sizeof(b),0);
               b[0]:=1; b[1]:=1;
               inc(i);
               ans:=mul(j);
               if i>k then break;
               j:=0;
          end;
     end;
     for i:=ans[0] downto 1 do write(ans[i]);
end.