def main():
    str_count = 0
    s = str(input())
    # print(s)
    first_c = s.split("c", 1) # 最初に"c"が出てきた時に、それ以降の文字のカウントをしたい。
    # print(first_c) 
    if len(first_c) == 1:
        print(-1)
    else:
        first_w = first_c[1].split("w", 1)
        str_count += len(first_w[0]) + 1
        # print(first_w)
        if len(first_w) == 1:
            print(-1)
        else:
            second_w = first_w[1].split("w", 1)
            # print(second_w)
            str_count += len(second_w[0]) + 2
            if len(second_w) == 1:
                print(-1)
            else:
                print(str_count)

            
        
    
if __name__ == '__main__':
    main()