C++ :: How To Find Position Of Certain Character In String

I need to find position of certain character in string, so i made a function but it doesn't do what i thought it would.

Consider this string:

std::string line = "<foo> <foo> <foo> <foo> <foo>"

I need to find position of a third '>' character so i can get:

std::string other = "<foo> <foo> <foo>";

This is my function that fails:

std::size_t find_third(const std::string& line) {
std::size_t pos = 0u;
for(std::size_t i = 0; i < 3u; ++i) {
std::string tmp = line.substr(pos);
pos = tmp.find_first_of('>');
} return pos;
}