According to 1973 constitution, who elects the president of Pakistan?

According to 1973 constitution, who elects the president of Pakistan?

آئین 1973 کے مطابق پاکستان کا صدر کون منتخب کرتا ہے؟
Explanation

Zulifqar Ali Bhutto introduced 1973 constitution in Pakistan on August 14, 1973.

According to 1973 constitution, Provincial assembly, National assembly, and senate elect the President.

Whereas the prime minister is elect by only national assembly.

Bicameral Legislature system was introduced for the first time in Pakistan in the constitution of 1973.