const
magic:int64=1000000007;
var
f:array[-1..1005,-1..1000] of int64;
n,m,k:longint;
i,j:longint;
t:longint;
r:longint;
function cgb(n,m:longint):longint;
begin
if m=0 then exit(n) else exit(cgb(m,n mod m));
end;
begin
fillchar(f,sizeof(f),0);
readln(n,m,k);
for i:=0 to n do f[i,0]:=1;
for j:=0 to m do f[0,j]:=1;
for i:=1 to n do
for j:=1 to m do
f[i,j]:=(f[i-1,j]+f[i,j-1]) mod magic;
t:=2*n*m+n+m;
r:=0;
for i:=0 to n do
for j:=0 to m do
begin
if ((f[n,m]-(f[i-1,j])*f[n-i,m-j] mod magic+magic) mod magic)=k then inc(r);
if ((f[n,m]-(f[i,j-1])*f[n-i,m-j] mod magic+magic) mod magic)=k then inc(r);
end;
if r=0 then
writeln(0)
else if r=t then
writeln(1)
else
begin
k:=cgb(r,t);
writeln(r div k,'/',t div k);
end;
end.