import streamlit as st

def main():
    st.set_page_config(page_title="Terms of Service Agreement", page_icon=":guardsman:", layout="wide")
    st.title("Terms of Service Agreement")

    agreed = st.checkbox("I agree to the terms of service")
    username = st.text_input("Enter your username")

    if st.button("Submit") and agreed and username.strip():
        st.experimental_rerun()
        st.session_state["user_name"] = username
        st.session_state["tos_agreed"] = True
        st.experimental_reroute("/congratulations")

    if not st.session_state.get("tos_agreed", False):
        return

    st.title("Congratulations!")
    st.write(f"Welcome to our platform, {st.session_state['user_name']}!")

if __name__ == "__main__":
    main()