4.2 Base RLE decimal

a = input()
sym_index,sym,d = -1,[],""
sym_count = [0 for i in range(len(a))]
for i in range(len(a)):
    if a[i]==d:
        sym_count[sym_index]+=1
    else:
        sym+=a[i]
        sym_index+=1
        sym_count[sym_index]+=1
        d=a[i]
for i in range(len(sym)):
    if sym_count[i]!=1:
        print(str(sym_count[i])+sym[i],end = "")
    else:
        print(sym[i],end = "")