s = list(input().split(',')) a = [] for i in range(len(s)): tmp = s[i].split(':') a.append((int(tmp[0]),int(tmp[1]))) a = sorted(a,key = lambda x:(x[1],-x[0])) #print(a) res = max(a[0]) for i in range(1,len(a)): if res<a[i][1]-a[i][0]: res = a[i][1] else: tmp = res - a[i][1] + a[i][0] res = a[i][1] + tmp if res>4800: print(-1) else: print(res)